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ANIMAL AND PLANT HEALTH INSPECTION SERVICE • UNITED STATES DEPARTMENT OF AGRICULTURE AGRICULTURE HANDBOOK NO. 48 5

PREFACE

The primary purpose of this manual is to Wood, W. D. Hunter, R. A. Cooley, and G. H. F. serve as a training aid and provide basic infor- Nuttall. mation on ticks and tick-borne diseases for A section on ticks, intended as the first part of veterinarians and animal health technicians a contemplated field manual on veterinary directly or indirectly involved in tick surveil- entomology for personnel of the Animal Disease lance, control, and eradication activities. It is not intended to be a definitive work on ticks of Eradication Division, was initially compiled by veterinary importance. Gerald Diamant, Robert K. Strickland, and the late W. G. Bruce. The section on ticks was Veterinary Services is especially grateful to issued in June 1961 and slightly revised in the many persons whose works have been con- August 1961. sulted in the preparation of this manual. With- out freely drawing on their publications, this The section on ticks was revised by Gerald manual could not have been compiled. Some of Diamant and Robert K. Strickland and issued the principal contemporary researchers in- in June 1965 as The Manual on Livestock clude Harry Hoogstraal, Jane Walker, Gertrud Ticks for Animal Disease Eradication Division Theiler, C. N. Smith, E. C. Loomis, Glen Kohls, personnel, ARS 91-49. Carleton M. Clifford, W. 0. Neitz, M. N. Kaiser, The present revision has been prepared by and P. R. Wilkinson. Earlier tick researchers Robert K. Strickland, Robert R. Gerrish, James include W. A. Hooker, F. C. Bishopp, H. P. L. Hourrigan, and Glen O. Schubert.

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CONTENTS

Page List of illustrations vi I. Introduction 1 II. Ticks and tick-borne diseases 1 Protozoal diseases 2 Bovine Piroplasmosis 2 Equine Piroplasmosis 2 Canine Piroplasmosis 3 The Theilerioses 3 Bovine Anaplasmosis 3 Rickettsial and Rickettsial-like diseases 4 Rocky Mountain spotted fever of man 4 Q Fever 4 Canine Ehrlichiosis 4 Bovine and Ovine Ehrlichiosis 4 Heartwater 5 Bacterial diseases 5 Tularemia 5 Spirochetosis of livestock and poultry 5 The relapsing fevers of man 5 Brucellosis 6 Viral diseases 6 Nairobi sheep disease 6 Louping 111 6 Colorado tick fever 6 III. Tick paralysis and Toxicosis 6 IV. Ticks as pests 7 V. Classification and description of ticks 8 VI. Biology and behavior 10 VII. Control and eradication 14 VIII. Regulations on importing and interstate movements of ticks.. 15 IX. Identification 15 X. The key and hov^ to use it 16 Terms used in the key 16 XL Key to families of ticks 20 Family Ixodidae 20 Morphological characteristics of the Family 20 Key to developmental stages of Family Ixodidae 21 Key to Genera of adults of Family Ixodidae 21 General comments 21 Genus Amblyomma 21 Morphological characteristics of the Genus 21 Key to males of the United States. 22 Key to females of the United States 22 General comments 22 Genus Aponomma 23

111 CONTENTS—Con. Page Morphological characteristics of the Genus 23 The species of Aponomma 23 General comments 24 Genus Boophilus 24 Morphological characteristics of the Genus 24 Key to the males of North America 24 Key to the females of North America 24 General comments 24 Genus Dermacentor 24 Morphological characteristics of the Genus 24 Key to the adults of the United States 25 General comments 25 Genus Haemaphysalis 26 Morphological characteristics of the Genus 26 Key to the adults of the United States 26 General comments 26 Genus Hyalomma 27 Morphological characteristics of the Genus 27 The species of Hyalomma 27 General comments 27 Genus Ixodes 27 Morphological characteristics of the Genus 27 The species of Ixodes 27 General comments 27 Genus Margaropus 28 Morphological characteristics of the Genus 28 The species of Margaropus 28 General comments 28 Genus Rhipicentor 28 Morphological characteristics qf the Genus 28 The species of Rhipicentor 28 General comments 28 Genus Rhipicephalus 28 Morphological characteristics of the Genus 28 The species of Rhipicephalus 28 General comments 28 Family Argasidae 29 Morphological characteristics of the Family 29 Key to developmental stages of Family Argasidae 29 Key to Genera of Family Argasidae 29 General comments 29 Genus Argas 29 Morphological characteristics of the Genus 29 The species of Argas 30 General comments 30 Genus Ornithodoros 30 Morphological characteristics of the Genus 30 Key to the adults mqst commonly found on livestock in the United States 30 General comments 30 CONTENTS—Con.

Page Genus Otobius 31 Morphological characteristics of the Genus 31 Key to the nymphs 31 Key to the adults ^ 31 General comments 31 XII. Collecting and preserving ticks 31 XIII. Hosts, distribution and diseases transmitted by selected ticks Hard ticks (Ixodidae) 33 Soft ticks (Argasidae) 35 XIV. Life history summaries of selected ticks of veterinary importance 36 Amblyomma americanum (Linnaeus), the Lone Star tick.. 36 Amblyomma cajennense (Fabricius), the Cayenne tick 37 Amblyomma hebraeum Koch, the Bont tick 37 Amblyomma maculatum Koch, the Gulf Coast tick 38 Amblyomma variegatum (Fabricius), the Tropical Bont tick 39 Argas versions (Oken), the Fowl tick 40 Boophilus annulatns (Say), the Cattle Fever tick 41 Boophilus decoloratus (Koch), the Blue tick 42 Boophilits microplus (Canestrini), the Tropical Cattle tick 43 Dermacentor albipictus (Packard), the Winter Tick 44 Dermacentor andersoni Stiles (Synonym, Dermacentor venustus Banks), the Rocky Mountain wood tick 44 Dermacentor nitens Neumann (Synonym, Anocentor nitens (Neumann), the Tropical Horse tick 45 Dermacentor occidentalis Marx, the Pacific Coast tick 46 Dermacentor variabilis (Say), the American dog tick 46 Haemaphysalis leachi leachi^^ (Audouin), the Yellow dog tick 47 Haemaphysalis leoprispalustris (Packard), the Rabbit tick 48 Hyalomma marginatum Koch, the Mediterranean Hyalomma 48 Ixodes ricinus (Linnaeus), the European Castor Bean tick 49 Ixodes scapularis (Say), the Black-legged tick 50 Ornithodoros coriaceus Koch, the Pajaroello tick 51 Otobius megnini (Dugès), the Spinose ear tick 51 Rhipicephalus appendiculatus Neumann, the Brown ear tick 52 Rhipicephalus evertsi evertsi Neumann, the Red-legged tick 53 Rhipicephalus pulchellus Gerstacker, the Zebra tick 54 Rhipicephalus sanguineus (Latreille), the Brown Dog tick 55 XV. Checklist of the ticks of the United States 56 XVI. References , 59 LIST OF ILLUSTRATIONS Page Hypothetical hard ticks 66 Hypothetical soft ticks 67 Dorsal view of the scuta and capitula of some female hard ticks 68 Schematic life cycles and disease transmission of ticks : Type I 69 Type II , 70 Type III 71 Type IV 72 Type V 73 Ornithodoros turicata: male 74 female 75 nymph 76 Otohius megnini: male 77 female 78 nymph 79 Amblyomma americanum: male 80 female 81 nymph 82 Amblyomma cajennense: male 83 female 84 nymph 85 Amblyomma imitator: male 86 female 87 Amblyomma Tnaculatum: male 88 female 89 nymph 90 Boophilus annulatus: male 91 unengorged female 92 partially engorged female 93 engorged nymph 94 Boophilus micropliis: male 95 female 96 partially engorged female 97 Dermacentor albipictus: male 98 female 99 nymph 100 LIST OF ILLUSTRATIONS—Continued Page Dermacentor andersoni: male 101 female 102 nymph 103 Dermacentor nigrolineatus : male 104 female 105 Dermacentor nitens: male 106 female 107 nymph 108 Dermacentor occidentalis : male 109 female 110 nymph Ill Dermacentor variabilis: male 112 female 113 nymph 114 Haemaphysalis leporispaliistris : male 115 female 116 nymph 117 Ixodes scapularis: male 118 partially engorged female 119 Rhipicephaliis sanguineus: male 120 unengorged female 121 nymph 122

May 1976

VIF

TICKS OF VETERINARY IMPORTANCE

I. INTRODUCTION

The threat of the introduction of ticks and marginatum, and H. truncatum. Many other tick-borne diseases into the United States is species of equal or unknown economic import- probably as great today as at any time in ance have also been detected. our history. The United States is no longer Ticks are of importance to man and his protected by the dual barrier of time and animals for two reasons : they are all parasitic space. Modern transportation has increased the and many are important transmitters of diseases chances of survival of ticks and other external to both man and lower animals. Ticks are the parasites on animals in transit. Today it is pos- most important vectors of a variety of disease sible to load animals on swift ocean vessels in agents to domesticated animals and are second Africa, Asia, and Europe, and in a few days only to mosquitoes as transmitters of diseases have them unloaded at one of our ports of to man. Ticks harbor protozoa, viruses, bacteria, entry. With air transportation — and more rickettsia, and toxins, and transmit these animals are being shipped by air each year—de- organisms to man and animals. parture to arrival is measured in hours rather Ticks are able to survive adverse conditions than days. and transmit diseases for a number of reasons : In earlier days, during the long, slow voyages they have a heavy, protective, chitinous cover- of sailing ships, the infected animals often died ing ; can withstand long periods of starvation ; or recovered during the voyage so that upon have a wide host range ; deposit large numbers arrival they were not often a threat to the of eggs; are relatively free from natural domestic livestock. The ticks usually completed enemies ; and are tenacious bloodsuckers. engorgement, dropped from the host, and were washed overboard before arrival at the port of Ticks act not only as vectors but also serve entry. as reservoirs of certain infectious agents. Since the end of World War II, the importa- Mammals and birds are the principal hosts of tion of exotic animals by zoological gardens, ticks, but reptiles and even amphibians are animal dealers, and individuals has created a parasitized by them. potentially dangerous situation. Too often these Despite their lack of wings, ticks have become exotic animals are infested with economically widely distributed throughout the world. This important species of ticks. For example, some dispersion is attributed to the movement of species found on animals at air, land, and their many hosts. About 10 percent of the ap- ocean ports of entry and on animals already proximately 800 known species of ticks are in zoological compounds include Amblyomma established in the United States. Of the 80 or so hebraeum, A, pomposum, A. variegatum, species found in the United States, about 20 are Boophilus annulatus, B. decoloratus, B. micro- of some veterinary importance. A check list of plus, Ixodes ricinus, Rhipicephalus appendicu- the ticks found in the United States is included latiis, R. bursa, R. evertsi, R. simus, Hyalomma in the manual (see page 56).

II. TICK AND TICK-BORNE DISEASES

Since ticks are the most important vectors of known to be established. This manual intro- disease agents affecting livestock, it is desirable duces some of the economically important ticks to have some general knowledge of the diseases, and tick-borne diseases, not only of the United the ticks which transmit them, and the geo- States but also of other areas of the world. graphical areas of the world where they *are Detailed information on the diseases, tick vectors, and distribution may be found in the Eradication is difficult because the cattle published papers cited in the references. fever tick can withstand long periods of starva- The tick-borne diseases are usually recog- tion—a single pair can produce several thou- nized as being in one of the following groups : sand offsprings in less than a year, and it protozoal, rickettsial, bacterial, and viral. Ticks parasitizes horses, mules, and deer as well as also produce tick paralysis, tick toxicosis, and cattle. serve as serious bloodsucking external pests. In addition to Babesia bigemina and B. argentina there are three other species of PROTOZOAL DISEASES Babesia affecting cattle throughout the world. These other Babesia are transmitted by one or Bovine Piroplasmosis more species of Ixodes, Rhipicephalns, and (Bovine Babesiosis, Cattle Tick Fever, Boophilus. Texas Fever, Redwater, Splenetic Fever) Equine Piroplasmosis In the New World bovine piroplasmosis, This disease, also called horse tick fever or commonly called cattle fever, is produced by babesiosis, affects horses, mules, donkeys, and Babesia bigemina and B. argentina, protozoan zebras. In horses the disease is characterized by parasites of the red blood cells. As the proto- fever, anemia, icterus, and often circulatory zoans multiply they destroy the red blood cor- and respiratory distress. There are two recog- puscles and thereby cause hemoglobinuria and nized types of equine piroplasmosis. anemia. This is accompanied by a rise in body In the United States the type of equine temperature, depression, loss of appetite and piroplasmosis most frequently encountered is body weight. The animal finally goes into a caused by Babesia caballi and is known to be coma and dies. In severe outbreaks mortality transmitted by Dermacentor nitens. Other ticks may approach 90 percent. When ticks feed on an are involved in the transmission in other areas infected animal, the ingested protozoa pass into of the world. The distribution of J?. caballi the reproductive organs of the female tick and includes all or parts of southern Europe, Asia, thence into the eggs. Larvae, or seed ticks, Russia, Africa, West Indies, Central America, emerging from these infected eggs thus become South America, and southern Florida. carriers and capable of transmitting the disease The second type of equine piroplasmosis is organisms to susceptible hosts. This is known produced by Babesia equi (=Nuttallia equi) as transovarian transmission — transmitting and is regarded as being more pathogenic than disease organisms from an infected female the type caused by B. caballi. It has been re- through the egg to the offspring. ported from all or parts of southern Europe, Prior to the successful cattle fever tick Russia, Africa, South America and Asia, and eradication program, Boophilus annulatiis and southern Florida. B. microplus were the most important external The tropical horse tick, D. nitens, is the only parasites of cattle in the United States. These proven natural vector of B. caballi in the were the only ticks involved in the transmission United States. It is also a suspected vector of of bovine piroplasmosis in North America. An B, equi in the West Indies and Florida. The only all-out eradication program was initiated by the other tick presently established in the United U. S. Department of Agriculture in 1906. By States known to be capable of experimentally 1943 the Boophilits ticks had been eradicated transmitting either type of equine piroplas- from the United States except for a narrow mosis is Rhipicephalns sanguineus. Fortunately, buffer zone along the Texas-Mexico border. R. sanguineus does not commonly feed on This buffer zone was placed under Federal and equines in the United States. Throughout State quarantine since reinfestations occur and the world several species of Dermacentor, an active surveillance and control program is Hyalomma and Rhipicephalns have been in- required to prevent spread of Boophilus ticks criminated in the transmission of both types of into free areas. equine piroplasmosis. Canine Piroplasmosis rate may be very high, often reaching 90 to 100 percent in susceptible animals. (Canine Babesiosis, Biliary Fever, Malignant Jaundice) In the Mediterranean coastal area and the Middle East a disease of cattle similar to East In the United States the brown dog tick, Coast fever is caused by T. annulata. Several Rhipicephalus sanguineits, is the vector of species of Hyalomma ticks are involved in the canine piroplasmosis, caused by the protozoan transmission. The mortality varies from 10 to Babesia canis. This tick is found throughout 90 percent, depending on the geographical area. most of the world and is probably the most Two other species, T, lawrencei and T, mutans, widely distributed of all species of ticks. It is are transmitted to cattle by several species of well adapted to the climate of southern United Rhipicephaliis in parts of Africa. At least two States. The brown dog tick can pass its entire species of Theileria have been reported from life cycle indoors, making it a very annoying sheep and goats throughout the world. Benign pest in kennels and homes. Although it is basic- strains of Theileria spp. have been reported ally a tropical or subtropical species and unable from cattle and deer in the United States. to survive outdoors throughout the winter in the northern States, the advent of central heat- Bovine Anaplasmosis ing in homes and kennels has enabled this tick (Gallsickness) to become a common pest throughout the year as far north as Connecticut and New York. Anaplasmosis was long believed identical with Parasitization of the blood cells by J5. canis bovine piroplasmosis. It was distinguished as a causes fever, inappetance, incoordination, and separate entity in 1910, when the disease and anemia in affected canines. Dogs that recover its anaplasma bodies were found in bovines may carry the organism in the blood for a year free of cattle fever. The precise nature of the or more, eventually lose the infection, and pathogenic organism that causes anaplasmosis become susceptible again. is not known. Many scientists believe the organism is a protozoan, others theorize that it The Theilerioses is a virus, or a rickettsia, or a microorganism belonging to a group of as yet unrecognized There are several diseases caused by protozoal and unclassified biological position. This micro- parasites of the genus Theileria. The organisms organism, Anaplasma marginale, multiplies in in the genus Theileria differ from Babesia in the red blood cells, and death of the host may the following respects : result from severe anemia. (1) They do not destroy the red blood cells, although they invade them during the While not the sole mechanisms of spread, acute phase of the disease. transmission studies have incriminated numer- (2) There is no multiplication of the organism ous species of ticks in the dissemination of in the red blood cells. anaplasmosis. Anaplasma marginale, like the (3) Multiplication of the organism occurs in causative agent of cattle fever, may be trans- the lymphocytes and the endothelial cells mitted from one generation of ticks to the next. of the lymph nodes, spleen, and liver. The suspected .tick vectors of primary impor- (4) There is no transovarial transmission of tance in this type of transmission in North the organism; transmission is stage to America are the Rocky Mountain wood tick, stage by 2-~host and 3-host ticks. Dermacentor andersoni (=D. venustus), and The most important of the theilerioses is East B, microphis. Coast fever of cattle which is a serious problem Stage-to-stage transmission in the same gen- in eastern and central Africa. This disease was eration has been recorded for the winter tick, once prevalent in South Africa, but reportedly D. albipictus; the American dog tick, D, vari- it has now been eradicated. The causative agent abilis; the black-legged tick, Ixodes scapularis; is Theileria parva and the primary vector is the brown dog tick, Rhipicephalus sanguineus; Rhipicephalus appendiculatus. The mortality and the fowl tick, Argas persicus. RICKETTSIAL AND RICKETTSIAL-LIKE far there is no evidence to incriminate them as DISEASES vectors in the United States. In southern Europe, Africa, and Asia, a Rocky Mountain Spotted Fever of Man related disease, boutonneuse fever (Marseilles fever, tick typhus), caused by Rickettsia conori, This disease, caused by an infection of is often a problem in humans. Two important Rickettsia rickettsi, is characterized by chills, vectors include the cosmopolitan Rhipicephalus high fever, pains in muscles and joints, and sanguineus and Haemaphysalis leachi of west- eruptions of livid spots on the skin. Dermacentor ern, central and southern Africa. Other ticks andersoni, the Rocky Mountain wood tick, is have been incriminated in the transmission, and the principal vector in the mountainous regions a variety of ticks and small mammals are of the Western United States and in the involved in maintaining the infection in nature. southern parts of British Columbia, Alberta, and Saskatchewan in Canada. The mortality Q Fever may vary from 20 to 80 percent in untreated (Query Fever) cases. This ubiquitous disease, caused by Coxiella The Rocky Mountain wood tick is a 3-host burneti, has been associated with many species tick and the life cycle is usually completed in of ticks. It is primarily a respiratory infection 2 years. Small mammals serve as hosts for the in man, and although it may be transmitted by larvae and nymphs. The adult ticks require the "bite" of an infected tick, transmission large mammals, preferably cattle, horses, deer, usually occurs as the result of the inhalation of and elk to complete their development. Man is dust or droplets contaminated directly or in- an accidental host. Animals of intermediate size directly by infected cattle, sheep, and goats. such as rabbits and badgers may serve as hosts Man may also be infected by the inhalation of for all three stages of the tick. The causative the organism in dried tick feces or by the agent of Rocky Mountain spotted fever may be ingestion of contaminated milk. Infection is transferred by ticks via the egg to successive usually not apparent in livestock. The reser- generations. The rickettsia is maintained in voirs in nature are ticks and a variety of small nature in a cycle between immature ticks and wild mammals. a variety of small wild mammals. The American dog tick, Dermacentor varia- Canine Ehrliehiosis bilis, is responsible for the spread of Rocky (Malignant Canine Rickettsiosis) Mountain spotted fever in Eastern United This is a septicémie disease of canines which States, particularly Maryland, Virginia, and is caused by Ehrlichia canis with Rhipicephalus North Carolina. sanguineus as the primary vector. The infective Three additional species of ticks that are agent is transmitted by all three stages of the known to transmit Rocky Mountain spotted tick as well as through the egg to the next fever in the United States are Amblyomma generation. Mortality rates as high as 90 per- americanum, Haemaphysalis leporispaliistris, cent have been reported. Canine ehrliehiosis has and Dermacentor parumapertus. Since the dis- been reported from the United States, France, tribution of A, americanum lies within that of Africa, Syria, India, and the West Indies. It Dermacentor variabilis, the exact role of A. probably occurs in most areas which have americanum as a vector of Rocky Mountain established populations of R. sanguineus. spotted fever in man is not known. The other two species, H. leporispalustris and D. paruma- Bovine and Ovine Ehrliehiosis pertus, are not found on man and are involved (Benign Bovine and Ovine Rickettsiosis) primarily as reservoirs and vectors of the Cattle and sheep each have a benign form of disease in nature among wildlife, especially ehrliehiosis caused respectively by Ehrlichia rabbits and hares. bovis and E, ovina. Bovine ehrliehiosis is com- Amblyomma cajennense and Rhipicephalus mon in South Africa where the vectors are sanguineus have been reported as vectors of Hy&kmvma spp. The disease has also been re- Rocky Mountain spotted fever in Mexico, but so ported from the United States. Ovine ehrliehiosis has been reported from Africa and Australia. Man and domestic animals are not involved In South Africa, Rhipicephalvs evertsi is the in the natural disease cycle of tularemia and vector ; where as in north Africa (Tunisia and become infected only when they accidentally Algeria) the vector is -R. bur sa. enter into it. The mortality in man is approxi- mately 6 percent. Heartwater Spirochetosis of Livestock and Poultry This rickettsial-like disease, caused by Cowdria ruminantium, affects sheep, goats, and In South Africa, spirochetosis has been re- cattle, but all ruminants may carry the causa- ported from cattle, sheep, goats, and horses. The tive agent, some without showing apparent causal agent, Borrelia theileri, is transovarially clinical signs of disease. Heartwater has been transmitted by Boophilus decoloratus and observed in Africa for at least 100 years and its Rhipicephalus evertsi, and produces a mild transmission by ticks has been known for some febrile disease. 70 years. The principal vectors are Amblyomma hebraeum in South Africa, A. variegatum in Avian spirochetosis is a highly fatal disease west, central, and east Africa; and A. lepidum of turkeys, pheasants, doves, and pigeons, and in the Sudan. Amblyomma gemma and A. is reported in many countries throughout the pomposum have also been incriminated. The world, including the United States. Transmis- disease agent is not transovarially transmitted. sion of the infective agent, Borrelia anserina The ticks become infected during the larval and is by several soft ticks of the genus Argas. nymphal stages and transmit the causative agent during one of the subsequent stages. The Relapsing Fevers of Man Mortality in heartwater varies from 50 to 90 In the United States, tick-borne relapsing percent. Losses are highest in sheep, goats, and fever of man is transmitted by at least four imported cattle. Persian and Africander sheep species of soft ticks of the genus Ornithodoros. are more resistant, and mortality is approxi- The disease is reported in limited areas of 13 mately 6 percent. Southwestern and Western States. There are several species of Borrelia involved and ap- BACTERIAL DISEASES parently each tick carries its own species or strain of the organism. Tularemia Like other species of Borrelia, the spirochetes (Rabbit Fever) are transmitted through the egg to the larval Tularemia, primarily a disease of rabbits and tick. Reservoirs of the disease include the rodents, is caused by Francisella tularensis, rodent hosts and Ornithodoros ticks. Reportedly Man often acquires the disease by direct con- the Borrelia may remain infective in starved tact when dressing diseased rabbits but may ticks for as long as 5 years. also be infected by tick bites or by contact with Man comes into contact with the disease when iirfected tick feces. In. addition t© ticks, blood- frequenting caves and other areas where the sucking arthropods, such as the deer fly ticks and their rodent hosts live. Transmission (Chrysops spp.), may be of importance in the is affected by the "bite" of some species of spread of this disease. There are reports of Ornithodoros or by the contamination of the serious outbreaks of tularemia in sheep pas- wound or skin with tick excretions in other tured on land with heavy infestations of the species. The mortality is generally 5 percent or Rocky Mountain wood tick, Dermxicentor an- less, except in very young, old, or debilitated dersoni. In the United States, the principal persons. vectors of the disease among rabbits and There are also endemic foci of tick-borne rodents, in nature, are several species of relapsing fevers reported from Mexico, Central Dermacentor, and Haemaphysalis leporispalus- America, South America, Europe, Asia, and tris. Reportedly, Amblyomma americanum Africa. In Africa, which probably has one of transmits tularemia to hunting dogs in the highest incidences of tick-borne relapsing Arkansas. fever, Ornithodoros moubata is the primary vector. This tick usually feeds at night and is known to occur in R. appendiculatus; re- remains hidden during the day in the earth portedly the virus can survive for about 21/2 walls and floors of native houses. It is often years in the adult stage of the tick. Mortality is detected by the presence of excreta marks on invariably high in the native Masai sheep the outside of cracks and crevices in the mud although it rarely exceeds 40 percent in walls. Merinos or Merino crosses.

Brucellosis Louping III Although ticks are not known to be involved Louping ill is a tick-borne virus disease of in the epidemiology of brucellosis in the United sheep transmitted by Ixodes ricinus. The States, there are reports incriminating them as disease is characterized by fever, nervous signs, possible vectors and reservoirs of brucellosis in ataxia, and paralysis. Cattle are occasionally livestock in other areas of the world. In Russia, infected ; horses, pigs, and man are suspectible several species of ticks have reportedly been to a lesser extent. The disease is reported from found naturally infected as well as being Great Britain and Ireland. Mortality in sheep experimentally infected with Brucella abortus averages about 10 percent on farms where the and B. melitensis. In Mexico, Tovar reports disease recurs from year to year, but may be ñnding Boophilus annulatus naturally infected very high in sheep flocks encountering the with Brucella abortus; he was also successful disease for the first time. in experimentally transmitting Brucella by allowing infected ticks to feed on normal guinea pigs. However, until the importance of ticks as Colorado Tick Fever vectors of brucellosis is clarified, care should be This is the most common human tick-borne taken in assigning them a definite role in the disease in western United States. It is charac- epidemiology of this disease. Ticks may play terized by a sudden onset, aching in the muscles, little, if any, role in the maintenance and headache, malaise, chills, a diphasic fever, and transmission of brucellosis in the United States. a marked leucopenia. There is usually an absence of the rash commonly associated with VIRAL DISEASES Rocky Mountain spotted fever. Although temporarily incapacitating, the rate of recovery Nairobi Sheep Disease is usually very high. Nairobi sheep disease is an infectious, non- The primary vector of the virus of Colorado contagious viral disease of sheep and goats in tick fever is Dermacentor andersoni. Other eastern and central Africa. The primary vector ticks found naturally infected are D. occiden- is Rhipicephalus appendiculatv^, but Ambly- talis, D. parumapertus, Otobius lagophihis, and omma variegatum and several other species of Haemaphysalis leporispalustris. Small mammals Rhipicephalus are also involved in the transmis- and immature ticks, especially D. andersoni, sion of the disease. Transovarial transmission maintain a reservoir of infection in nature.

III. TICK PARALYSIS AND TOXICOSIS

Tick Paralysis paralysis that usually leads to incoordination Man, domesticated animals, and birds are and collapse within 4 to 7 days of attachment subject to tick paralysis in North America, and feeding of the tick. In many instances, the Europe, Africa, and Australia. While the true symptoms subside if ticks are removed from nature of the casual agents is not known, they aniiÄ^s before ipÄi*€kj^is hae^ pi^egresfi^d toe act like neurotoxins producing an ascending far. If the ticks are not removed, the infested man or animal dies. Studies with these toxins Tick Toxicosis indicate that they cannot be transferred from There are several forms of tick-borne toxi- affected animals to healthy ones. Although tick cosis which are distinct from tick paralysis. paralysis is primarily produced by the engorg- Evidence indicates that these conditions are ing females, the immatures of Ixodes holocyclus caused by toxins produced by some species or and Argas persicus can also produce paralysis. strains of ticks. As with tick paralysis, the tick-borne toxicoses cannot be transmitted by The tick most frequently involved in tick contact with affected animals, nor can they be paralysis in North America is the Rocky transmitted by blood inoculations from affected Mountain wood tick, Dermacentor andersoni. to susceptible animals. Serious livestock losses have been reported Sweating sickness is one of these toxicoses, and it differs from the others in that it is the from western Montana, Idaho, Oregon, and only one in which the affected animals exhibit British Columbia. Most human cases are in a profuse, moist eczema and hyperemia of the children under 7 years of age, and a mortality visible mucous membranes. Thiö is primarily a rate of about 12 percent has been reported. In disease of calves less than a year old. Mortality the Eastern and Southern United States varies from 30 to 70 percent. The tick involved Dermacentor variabilis, Amblyomma ameri- in Africa is Hyalomma truncatum. The clinical canum, and A. maculatum also produce tick disease has also been reported from southern paralysis in man and dogs. Infestation with India and Ceylon. only one tick may produce paralysis in a sheep, In South Africa, another distinct tick toxi- dog, or human. Infestation with many ticks is cosis, which is caused by a leukocytropic toxin, usually required to produce paralysis in cattle— is conveyed by Rhipicephalus appendiculattis. At least two other mild, non-fatal toxicoses of which seem more resistant. In South Africa, cattle, sheep, and pigs have also been observed Ixodes rubicundus produces a type of tick in Africa. In Australia, very heavy infestations paralysis very similar to the paralysis produced of Boophilus microplus on cattle were reportedly by Dermacentor andersoni in North America. capable of producing clinical signs and Australian tick paralysis is produced by /. pathological changes suggestive of tick-borne holocycltts. toxicosis.

IV. TICKS AS PESTS

As well as acting as vectors of disease- to heavy infestations of ticks, include those producing organisms, ticks may cause con- caused by "tick worry" and hide damage. siderable mechanical injury, producing wounds Undoubtedly, the classic example of heavy susceptible to secondary bacterial invasion or tick infestation was reported in 1911 from South Africa where Sir Arnold Theiler, the screwworm infestation. Ticks also devour large distinguished veterinarian, collected half the quantities of blood. Severe infestations can Boophilus decoloratus from a horse which had cause anemia, loss of weight, and even death. died of acute anemia ; the ticks removed from Other losses on domestic animals, attributable the horse weighed 14 pounds. V. CLASSIFICATION AND DESCRIPTION OF TICKS

Ticks belong to the class Arachnida and are • Fused head and thorax. related to scorpions and spiders. Ticks and • Eyes, when present, small and simple. mites belong to the order Acariña and are • Mouth parts set off from the body as a closely related. The order includes two families false head or capitulum consisting of a of ticks : the hard ticks, Ixodidae, which have characteristic hypostome armed with longi- a scutum ; and the so-called soft ticks, Argasi- tudinal rows of recurved *'teeth" or den- dae, which lack a scutum (see classification ticles, highly specialized chelicerae with chart page 91). Ticks are not insects. apical cutting digits, and palps; but no Ticks are differentiated from adult insects by antennae or mandibles. certain well-defined characteristics. The adult • Body wall of argasids leathery. In ixodids, insect has three body segments : a hard chitinized shield (scutum) covers • Head with eyes and antennae. the back of the male ; in the female, nymph, • Thorax with six legs, two pairs of spiracles, and larva, only a small shield is present and usually one or two pairs of wings. dorsally behind the capitulum, the rest of • Abdomen with genitalia and usually eight the body wall being extensible, allowing pairs of spiracles. the tick to enlarge greatly during feeding. Ticks are small, wingless, bloodsucking • Adults and nymphs with eight legs ; larvae parasites that have : or seed ticks with six legs.

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< i VI. BIOLOGY AND BEHAVIOR

There are four stages in the life cycle of the host, and return to a protected area away from tick: the egg, the 6-legged larva or seed tick, the host. The spinose ear tick, Otohins megnini, the 8-legged nymph, and the adult (male and is an exception and could be called a 1-host female). Transition from one stage to the next tick. is made by one or more moltings (shedding of the cuticle). The steps in tick development are Mating not particularly restricted to seasons. Species adaptation, temperature, moisture, and avail- Mating may take place on or off the host and ability of host animals influence their duration. during or after engorgement. With Argasidae, The number of generations may vary from for example, copulation takes place after the three or» four a year in the 1-host species such adults have fed and left the host. With Ixodidae, as the tropical cattle tick, Boophilus microplus, Population usually occurs on the host, after to one a year in the Argasidae—or even one which the females appear to engorge more every 2 or 3 years in some 3-host species, such rapidly. as the Rocky Mountain wood tick, Dermacentor After mating and engorgement the female andersoni. drops from the host and crawls to a protected Hard ticks are often referred to as being 1-, place to oviposit. Under favorable climatic con- 2-, or 3-host ticks : ditions, oviposition may begin within 2 days or, The 1-host ticks spend their entire develop- in cold weather, may be delayed for weeks or mental period, from young larvae to even months. mature adults, on one animal. Example : The cattle fever tick, Boophilus annulatus. Oviposition and Incubation The 2-host ticks attach as larvae and com- The gravid female hard tick readies herself plete development through the nymphal for egg-laying by bending the capitulum down- stage. The replete nymph then drops wards so that it lies along the ventral surface from the host, molts to the adult stage, of the body near the genital opening. A vesicle, and later seeks a second host to complete the Gene's organ, is everted from between the development. Example: The red-legged basis capituli and scutum. The Gene's organ, tick, Rhipicephaliis evertsi. which enlarges into two lobes, contains glands The 3-host tick feed to repletion as larvae that secrete a waxy material. As the eggs are on one animal, drop to the ground, and extruded from the genital aperture, they are molt to the nymphal stage; as nymphs, received by these extended lobes and coated with attach to another animal and engorge, the waxy secretion. This protects the eggs from and again leave the animal to molt ; and dehydration and enables them to form an finally, as adults, feed on a third animal. adherent mass. Example: The American dog tick, Der- While female hard ticks engorge only once macentor variabilis. and die shortly after the completion of oviposi- The above designations do not usually apply tion, most soft tick females engorge a number to soft ticks since their feeding habits are quite of times and oviposit after each feeding. The different from those of the hard ticks. Soft ticks number of eggs laid by ticks vary by species. could be referred to as multihost ticks. Some For example. Argos persicus lays as many as soft ticks, such as Ornithodoros coriaceus, may seven batches of eggs; the number of eggs is have as many as seven nymphal stages with usually 150 to 250 per batch up to the fourth each stage feeding briefly. The female Argos batch but declines to less than half that number persicus may feed as many as seven times and with the last two batches produced. On the deposit a small batch of eggs following each other hand, Boophilus microplus lays a single feeding. Generally, the larval stage of soft batch of approximately 4,500 eggs. Although ticks may attach and feed on the host »for well above the average for hard ticks, one several days, but the nymph and adult normally female Amblyommo nuttolli reportedly de- feed for 30 minutes up to 2 hours, leave the posited 22,891 eggs in a single "sitting." 10 The incubation period is primarily determined most species nymphs tend to live longer. In by temperature. In the hard ticks this may those species that molt upon the host, molting range from about 2 weeks up to almost 7 takes place following engorgement and a short months. In tropical or subtropical areas, the resting period. In those species that leave the incubation period is usually relatively short and host, the molt may occur within 2 weeks or constant. However, in areas with a temperate may be delayed for several months. All hard climate, the incubation period may be only 2 or ticks have only one nymphal stage, but all soft 3 weeks if the eggs are produced in the summer, ticks undergo several nymphal molts, ranging or may be prolonged for many weeks or months from two to seven, with an average of three. if the eggs are layed in the autumn or early winter. For instance, the Boophilus annidatus Adult female, which drops from the host in Septem- ber, may deposit eggs which do not hatch until In those species that molt on the host, the the following March. adult female merely crawls from the nymphal skin and re-attaches at another site. The male Larva sheds the nymphal skin, re-attaches and feeds Following hatching, the larvae, or seed ticks, for a short time, then seeks a mate. usually remain clustered near the place of The behavior of adults of those species that emergence. This is a protective measure to pre- leave the host as nymphs to molt are similar to vent desiccation and to insure survival. Larvae those of the larvae and nymphs, except that the seldom feed within a week after hatching. unfed adult is usually capable of surviving When they are ready to feed they are often much longer without a blood meal than either found awaiting a host upon blades of grass, the nymph or larva. small trees, or bushes. Upon the approach of a Copulation of hard ticks usually occurs on suitable host, the larvae are alerted by their the host ; it generally precedes female engorge- sensory organs and become very active and ment and apparently inñuences the rapidity of attempt to crawl upon the animal. Larvae seem its completion. Female hard ticks may engorge to be stimulated most strongly by carbon and drop within a few days of attachment or dioxide and odors, but vibrations, air currents, remain on the host for 30 days or longer. interrupted light, warmth, and moisture are Apparently the females which remain attached factors which alert the tick to the presence of a for long periods fail to find mates. Males fre- host. Having found a host, the larvae may quently remain upon the host much longer and quickly seek out their favored site for attach- thereby ensure ready mates for virgin females. ment, or may wander over the host for several In contrast, mating of soft ticks occurs away days before finding a suitable place to feed. from the host—on the ground or in a protected Some species attach almost exclusively in the area. ear of the host; some prefer areas where the skin is comparatively thin ; while others attach Feeding Habits almost any place on the host. The larvae feed, and when engorged, most Ticks are obligatory parasites and require species of hard ticks drop from the host to tissue fluids and blood for development. In molt. They make their way to some protected feeding, most ticks attach to a preferred part area and become quiescent. Depending upon of the host. Some favor the dewlap, shoulders, temperature and humidity, molting to the and the region between the legs. The tropical nymphal stage may take from 5 days to several horse tick, Dermcicentor nitens, prefers the ear weeks or longer. The engorged larvae of 1-host but attaches to other parts of the body. The ticks remain on the host and molt after a short spinose ear tick, Otobitts megnini, attaches only quiescent period. deep in the external ear. The red-legged tick, RhipicephaltLs evertsi, feeds deep in the ear in Nymph its larval and nymphal stages and under the The activities and habits of nymphs are base of the tail or between the hind legs as an similar to those of the larvae, except that in adult.

11 Ticks attach by cutting through the skin of The disease agent is usually transmitted from the host with the digits of the chelicerae and the infected tick to the host via the salivary anchor by inserting the hypostome into the secretions. wound. The rapidity of feeding varies con- Soft ticks have coxal organs, sometimes siderably in different species and in different called coxal glands, which may have a role in stages of the same species. Feeding in female the spread of pathogenic microorganisms by hard ticks is usually a gradual process until some species of soft ticks. The coxal organs the final day of feeding; then the body rapidly open between the first and second pair of legs. fills with blood. Most female hard ticks feed on Their function is to filter off excess liquids and the host for 7 to 12 days and under certain salts from the blood meal soon after ingestion. conditions longer—but rarely less than 5 da^s Within 30 minutes, soft ticks may ingest a for complete engorgement. New cuticle is de- volume of blood which is several times the veloped during the slow feeding in order to tick's original body weight. During feeding, the accommodate the large volume of blood ingested. cuticle stretches to accommodate this large Hard tick larvae and nymphs usually feed for amount of fluid. The coxal organs enable the shorter periods than females. Male hard ticks soft tick to rapidly reduce the total intake become only slightly distended ; they are inter- volume to a level which best suits its needs. In mittent feeders and may remain on the host for Ornithodoros moubata the coxal discharge be- weeks or even months, as with Amblyomma gins about 15 minutes after the tick has begun variegatum, during which time several small to feed and may continue intermittently for blood meals are taken. about an hour after the completion of feeding. The nymphal and adult stages of soft ticks The spirochetes of relapsing fever pass from normally complete engorgement within 30 the infected tick in the coxal fluid on to the minutes to 2 hours; whereas, the larval stage skin of the host. They may then penetrate the usually feeds for periods varying from 5 to 30 intact skin or enter the wound made by the days. tick. Some species of soft ticks do not excrete During attachment and feeding, salivary coxal fluid until after they have left the host. secretions are Injected into the wound, ap- Hard ticks do not possess coxal organs. parently to aid in penetrating the host's skin Engorging ticks void excretory products and in preventing the coagulation of blood and which may contain pathogenic organisms that body fluids so that they can be readily ingested can enter the animal body through the tick-bite by the tick. The salivary secretions of some punctures or other breaks (or wounds) in the ticks are very irritating to the host. The skin. The careless removal of ticks from the pajaroello tick, Ornithodoros coriacens, pro- host may result in the rupture of the tick's duces an especially painful "bite" which may body with the release of gut contents around remain inflammed for days. the wound. Tularemia may be transmitted by From the standpoint of disease transmission both of these methods. and tick control, it is important to know that Tick-bite wounds predispose the host to the immature stages of a particular tick species infections and increase susceptibility to screw- may not feed on the same host species as do worm attack. the adults. For example, the adults of Derma- centor variabilis commonly attack livestock, Longevity man, and dogs; whereas, the immature ticks are almost always found on small rodents, Many species of ticks are able to survive for especially mice. long periods without a blood meal. Nymphs usually live longer than larvae, and adults live longer than nymphs. The adult fowl tick has Tick Secretions and Disease lived without food in vacant chicken houses for Transmission 37 months and then oviposited following a Salivary secretions play a most important blood meal. The relapsing fever tick, Omitho- role in the transmission of disease by serving doros turicata, has lived more than 3 years in as a medium of transport for the causal agents. jars of sand. Unfed larvae of the red-legged

12 tick can survive for 7 months, and unfed adults ability to withstand long periods of fasting, the for 14 months. The unfed adults of Dermacentor capacity to produce an enormous number of variabilis have been observed to survive up to eggs, and adaptation to a wide range of hosts. 1,053 days under outdoor conditions in eastern All one-host ticks, such as Boophilus spp., United States. Under experimental conditions, Dermacentor nitens, and D. albipictus, have the larval stage of D, variabilis may live more adapted themselves to molt on the host. The than a year without food; the nymphal stage elimination of the need to seek a second and was observed to live for 584 days without feed- third host diminishes the threat of species- ing. However, it should be emphasized that, in extinction in one-host species. most of these extreme instances of long survival Ticks have also synchronized many of their periods, these surviving ticks were not tested activities with those of the host. Rabbits as to their ability to feed and to carry on to generally remain inactive in their nests dur- the next stage. ing the day. The rabbit tick, Haemaphysalis The longevity of some species may be greatly leporispahistris, adjusted to the habits of its prolonged by reduced temperatures in the host by leaving the rabbit during the day. Thus, autumn and winter months of temperate after hatching or molting, these ticks have little regions. The activity of most, but not all, ticks difficulty in finding the host when they are is usually suspended during the cold months of ready to attach. In addition, the larval and the year. For example, Boophilus annulatus is nymphal stages of the rabbit tick very success- inactive during the winter ; on the other hand, fully use several species of ground-inhabiting Dermacentor albipictus is primarily active birds as hosts, while using rabbits as preferred during this period and is commonly called the hosts for the adult stage. winter tick. There is considerable variation in The engorged larvae of the fowl tick, Argas the longevity of Boophihis annulatus, depending persicus, have made another adaptation for on the season of the year; unfed larvae sur- survival. They are globular in shape until a few vived as long as 246 days during cool weather hours before dropping; the larvae then flatten but lived from only a few days up to 100 days into the typical Argas form that permits them during mid-summer. to crawl rapidly into protective crevices. Moisture is important in the longevity of The nymphs and adults of Argas persicus are hard ticks. Its complete absence is highly de- nocturnal in their feeding habits. To escape structive. On the other hand, too much mois- being devoured by chickens, they hide in cracks ture, particularly following a long fasting and crevices during the day, emerge at night to period, permits the growth of fungi on ticks feed for 30 minutes to 2 hours on the birds, and that is often fatal. return to their hiding places before the fowl become active. The longevity of any one or all stages in the Where ticks feed on the host is important in life cycle of a species of tick must be taken into their survival. For example, the spinose ear consideration when formulating a control or tick and the tropical horse tick attach deep eradication scheme. Failure to do so may very inside the ear. Species of Haemaphysalis found well result in something less than control or on quail, meadow larks, and ground-feeding eradication. birds customarily attach to the head, from which they are not readily dislodged. Instincts and Adaptations Female hard ticks can speed up the final Ticks are rigidly bound by instinctive be- phase of engorgement. The female Boophilus havioral patterns ; nevertheless, they have made microplu^ feeds leisurely, taking several days interesting adaptations for survival. Leaving to become about one-third engorged. Then, one host to molt, with the necessity of waiting within a few hours, she normally completes for a second or commonly a third host, results in engorgement and drops from the host. Possibly high tick mortality. This hazard has been over- this is a defensive mechanism to reduce the come to some extent in certain species of ticks by chance of the engorged female being crushed the development of one or more of the follow- by the host or attacked by birds such as the ing : an increased resistance to heat or cold, the oxpecker and cattle egret.

13 VIL CONTROL AND ERADICATION

Natural Control systemics. The use of systemics is a compara- The tremendous reproductive potential of tively new approach to pest control. A systemic ticks is mitigated by climate and by predators pesticide may be defined as a chemical which, and parasites. Without these natural controls, when administered to an animal as a spray, dip, tick populations build up to great numbers. injection, bolus, drench, or feed additive, is absorbed into the body tissues, either in its Temperature and moisture are principal agents affecting ticks. Cold weather, particularly original form or as a metabolite, and is toxic to prolonged cold, harms some species of ticks, susceptible parasites feeding on such tissues. mainly by killing them outright but also by Most species of ticks can be effectively con- prolonging their inactivity on the ground, trolled by the proper use of pesticides. "Effec- where they are more prone to attack by pre- tively controlled" here means the reduction of dators. Excessive heat, dryness, or rainfall have tick populations to the point where they are an adverse effect on some species. of little or no economic importance. It differs Wild birds, domestic fowl, rats, mice, ants, from eradication which resulta in the complete and at least two species of parasitic wasps play annihilation of a species from a defined geo- a part in the natural control of ticks. graphical area—as with the cattle fever tick. Research and field observations of cattle in- A large number of pesticides are effective dicate that purebred Brahman (Bos indiciis) against ticks. They include ronnel, crotoxyphos, and Brahman crosses have a greater resistance coumaphos (Co-Ral®,) ^ dioxathion (Delnav®), to tick infestation than the European breeds toxaphene, malathion, and many others. The (Bos taurus). The mechanism of such resistance pesticide of choice will be determined by may not yet be fully understood, but the knowl- several factors, such as species of animal—cat- edge that some species or breeds are more re- tle, horses, and swine—^the type of animal— sistant to tick infestation may be useful in dairy or beef—and the cost of pesticide used. contending with tick problems. Consideration must be given to compliance with Pasture rotation may achieve control or the Federal Food, Drug and Cosmetic Act eradication by starving the ticks. However, in which regulates pesticide residues in raw agri- view of the longevity of most species, pasture rotation without supplemental measures is cultural products, including meat and milk. If seldom practicable. dipping is part of an official USDA Veterinary Services program, only those chemicals per- mitted by Veterinary Services may be used. Chemical Control No attempt is made here to elaborate on the The most effective method of tick control is subject of pesticides and their uses. Instruc- by the use of chemical pesticides. Since the usual method of tick dispersion is by movement tions on vat management and the use of per- of the host, pesticide control can be effectively mitted pesticides for the control or eradication used with quarantine and regulation of animal of ticks and insects of concern to Veterinary movements. The combination of pesticides and Services are issued as needed. quarantine is essential in an eradication effort. Treatment of tick-infested premises, where ex- ^ Trade names are used in this publication solely for tensive acreages are not involved, may also be the purpose of providing specific information. Mention included with other control measures. of a trade name does not constitute a guarantee of warranty of the product by the U. S. Department of Chemical control involves the use of pesti- Agriculture or an endorsement by the Government over cidal sprays, dips, dusts, aerosols, smears, or other products not mentioned.

14 VIII. REGULATIONS ON IMPORTING AND INTERSTATE MOVEMENT OF TICKS

The Animal and Plant Health Inspection condition of issuance of permits, the permittee Service of the United States Department of shall agree in writing to observe the safeguards Agriculture has the responsibility for regulat- prescribed by the Department of Agriculture ing the importation and interstate movement of for public protection with respect to the par- animal disease-producing agents and animal ticular importation or transportation. disease vectors used in research of both human Essentially then, anyone wishing to import and animal diseases. It is essential that disease- live ticks or receive live ticks from another producing agents and vectors, including all live State must first obtain a permit from Veterinary ticks, are handled in a manner that does not Services. Ticks preserved in 70 percent alcohol endanger the health of domestic livestock and or other preservatives are not subject to the poultry. regulations and, therefore, may be imported or The authority for regulating such movements moved interstate without a permit. is contained in Part 122 of Title 9, U. S. Code Individuals wishing to import or transport of Federal Regulations. The regulation states live ticks interstate or desiring additional in- that no organisms or vectors of such organisms formation on the movement of disease organisms shall be imported into the United States or and vectors should direct their inquiry to : transported from one State or Territory or the District of Columbia to another State or Terri- Veterinary Services, APHIS tory or the District of Columbia without a per- U. S. Department of Agriculture mit issued by the Secretary of Agriculture and Federal Building in compliance v^ith the terms thereof. As a Hyattsville^ Maryland 20782

IX. IDENTIFICATION

The accurate identification of ticks is a pre- Nevertheless, Veterinary Services veterinarians requisite to their control and eradication. and animal health technicians can become Identification is also essential to justify long, familiar with the biology and identification of costly eradication programs, and the imposition the more common livestock ticks in the United of rigid quarantines. States. Unfortunately there are not now, nor are there likely to be, simplified keys or procedures An explanation of all characters will be found for the rapid creation of identification experts. on pages 16-20. Drawings of hypothetical ticks The identification of the numerous species of showing the location of key characters appear ticks is a matter for the trained taxonomist. on pages 66-68.

IS X. THE KEY AND HOW TO USE IT

The key to the identification of ticks presents Again, let us assume that the tick you have important characters of ticks arranged to before you has eight legs and a genital aper- facilitate identification. This key is for adult ture : it is an adult. Then, proceed to the key to ticks only and primarily for ticks of veterinary the genera of adults of the family Ixodidae on interest in the United States. page 21. Start with couplet 1. The important It will be noted that the key is arranged in character here is the anal groove—is it in front couplets, each couplet giving a choice of two of the anus, does it curve behind the anus, or alternate characters or two alternate groups of is it absent? The specimen tick has a small characters. Start with the first couplet and groove behind the anus, so proceed as indicated proceed to the couplet indicated by the number to couplet 2. Here the choice is between a palpus following the appropriate character, and so on, with the second segment projecting con- until the final determination is made. For ex- spicuously to the side or a palpus without such ample, place the specimen under the microscope projection. The tick fits into the second cate- topside (dorsum) up; focus the microscope and gory, so proceed to couplet 3. Here the choice is adjust the light on the tick. Have the drawing mainly between a hexagonal (six-sided) basis of a composite tick with parts labeled (pages 66-67) and the explanation of terms (pages capituli or one not six-sided. The basis capituli 16-20) handy for ready reference. on the specimen is rectangular, so proceed to Look at the first page of the key (page 20) couplet 7. Look at the palps under the micro- and note that the first thing to determine is scope—are they short with the second segment whether the specimen under the microscope is a not twice as long as its width ? You immediately hard tick (Ixodidae) or soft tick (Argasidae). see that your specimen fits the first description, Compare the characters in this couplet, then therefore you identify the tick as belonging to look at the tick. For discussion purposes, let us the genus Dermacentor. Now turn to page 24. assume that the tick has a scutum (shield) and Check the specimen with the "Morphological the capitulum (head) is at the anterior end of Characteristics of the Genus" under "GENUS the body. Therefore, it is a hard tick (Ixodidae) DERMACENTOR." If they all fit, you can be and the reference is to page 21. Next, determine certain you have keyed the specimen to the the developmental stage—larva, nymph, or correct genus. Proceed now in the same manner adult (male and female). Remember, the keys through the key to the species of Dermacentor in this manual are only for the identification of and you will identify the tick as Dermacentor the adult stages. variabilis.

Terms Used in the Key Accessory shields : Paired, projecting, sclerotized structures on venter, lateral to the adanal shields in males of Boophiltts, Rhipicephalus and Hyalomma. Adanal shields : Paired, projecting, sclerotized structures on venter, lateral to the anus in males of Boophilus, Rhipicephalus and Hyalomma. Anal groove : Semicircular groove curving around the anus in some genera of Ixodidae (hard ticks) ; in Ixodes curving in front, in other genera curving behind or absent. Anterior : Toward the head end. Anus: Posterior opening of the alimentary tract, situated on the median line posterior to the last pair of legs. Basis capituli : Basal portion of capitulum on which the mouth parts are attached. May be of various shapes: hexagonal, rectangular, subrectangular or sub- triangular in hard ticks and always attached to anterior of body. In soft ticks, located ventrally in adult and engorged nymph, anteriorly in larva.

16 Camerostome : Cavity or depression in which the capitulum of soft ticks is situated. Usually not well-defined in engorged specimens. Anterior movable portion of body of hard ticks, including basis capituli, Capitulum : palps, hypostome, and chelicerae of hard ticks. Located ventrally in adult and engorged nymph of soft ticks, anteriorly in larvae. Caudal process : Distinct projection arising from median posterior end of the body in males of some species of Boophilus, Rhipicephalits, and Margaropus. Cervical grooves : Pair of grooves in the scutum extending posteriorly from the inner angles of the scapulae. May be continuous or interrupted, shallow or deep, faint or absent. Cheeks : Paired flaps at the sides of the camerostome in some species of soft ticks. Chelicerae Paired structures lying dorsally to hypostome which complete the cylin- (sing- Chelicera) drical mouth parts that are inserted when the tick feeds. Chitin : The hard parts of the tick body formed from a colorless secretion pro- duced by the epidermis. Chitinized : Filled in with or hardened by chitin. Chitinous tubercles : Small, chitinized, rounded lobes on the posterointernal angle of the fes- toons of Amblyomma cajennense and sometimes A. maculatum. Cornu (pi. cornua) ; Small projections extending from the dorsal, posterolateral angles of the basis capituli. Coxae : Small, sclerotized plates on the venter representing the first segment of (sing. Coxa) the leg to which the trochanters are movably attached. From anterior to posterior, the coxae are designated by Roman numerals I, II, III, and IV. Bifid coxae are those that are cleft, divided, or forked. Coxal organs : Called coxal glands by some authors and are present in members of the family Argasidae but absent in members of the family Ixodidae. The external openings of the coxal organs are located between coxae I and II. Cuticule, or cuticula : Outer covering of a tick. Also called the integument. Denticles : Small, recurved projections or **teeth" on the ventral side of the hypos- tome. (See dentition.) Dentition : Refers to the presence of denticles on the ventral side of the hypostome. The numerical arrangement of the files or rows of denticles is expressed by the dentition formula. Thus, dentition 3/3 means that there are three longitudinal rows of denticles on each side of the median line of the hypostome. Difference in form, color, etc., between individuals of the same species, Dimorphism : more particularly between sexes. Distal : Farthest from the point of attachment or origin. Dorsal : Pertaining to the back or top of the body. Dorsal humps : Protuberances on the dorsal surface of the segments of the legs, but not including the subapical dorsal protuberance. Dorsal prolongation : The posterodorsal extension of the spiracular plate.

17 Dorsum : The entire dorsal surface of the body. Emargination : Anterior indentation or cutout place in the scutum between the scapulae that receives the basis capituli. Engorged : Enlargement or distention of a tick follov^ing a blood meal. Since the scutum is short in the larva, nymph, and female hard tick (covering about half the dorsal surface in the unfed specimen), the body is capable of pronounced distention. As the body fills with blood, the relative size of the scutum is reduced. In a fully engorged female hard tick, the scutum may appear only as a small plate on the anterior of the body. In the soft tick, the scutum is absent and both sexes may become enlarged, although not usually to the extent of the engorged female hard tick. Festoons: Uniform rectangular areas, separated by distinct grooves, located on the posterior margin of most genera of the hard ticks. Very distinct areas in unengorged specimens, but may not be visible in fully engorged females. In some species of Hyalomma, festoons may be reduced in number and partially coalesced. Festoons are not present in Boophilus and Ixodes. Files: Longitudinal rows of denticles or "teeth" on the ventral surface of the hypostome. Genital aperture : External opening of the genital organs. Located anteriorly on the ventro- median line, posterior to the basis capituli. Goblets : Small, round structures located in the spiracular plate. They may be very small and numerous as in Dermacentor variablis, or relatively large and few was in D. nitens. Hexagonal : Having six sides. Hood: Anterior projection of the integument on some soft-bodied ticks. Hypostome : Median ventral structure of the mouth parts that lies parallel to and between the palps and is immovably attached to the basis capituli. It bears recurved "teeth" or denticles. (See dentition.) Inornate : Absence of a color pattern on the scutum. Integument : Outer covering or cuticle of the tick's body. Lateral : Toward the side. Lateral groove : The groove running along the sides of the scutum in both sexes—may be continuous or interrupted. Legs : Segmented appendages of which nymphs an^^adults have four pairs and larvae have three pairs. From anterior to posterior the legs are identified by Roman numerals I, II, III, and IV. The segments from the proximal (next to the body) to the distal end are called coxa, trochanter, femur, tibia, metatarsus, and tarsus. Macula : Large sclerotized structure located in the spiracular plate of adult ticks. It may be of variable size, shape, and location. Mammillate : With nipplelike protuberances or processes. 18 Marginal groove : In females, the groove which runs along the sides of the body starting near the posterolateral border of the scutum. Medial : Toward the median axis of the body. Median : The longitudinal axis that divides the body. Morphological : Pertaining to form or structure. Ornamentation: Enamel-like color pattern that is superimposed on the base color of the integument in hard ticks. When present, this color pattern may be white to dirty white in Dermacentor or may be an intense copper or bronze color with touches of yellow or green in some Amblyomma. Ornate : Definite color pattern superimposed on the base of the integument in hard ticks. (See ornamentation.) Palps or palpi Paired articulated appendages located anterolaterally upon the basis (sing, palpus) capituli and lying parallel with the hypostome. Four distinct segments are present in soft ticks. In all hard ticks the fourth segment is reduced to a small hair-crowned papilla lying in a cuplike depression of segment 3. The sequence of numbering of the segments is indicated by Arabic numerals 1, 2, 3, and 4: 1 being the proximal segment (closest to the basis capituli). Periphery : Circumference or outer margin. Poröse areas : A pair of pitted areas, usually depressed and oval, on the dorsal surface of the basis capituli; present in all adult female hard ticks; absent in male and immature stages. Posterior : Toward the rear end. Protuberance : Any elevation above the surface. Proximal : Nearest to the point of attachment or origin. Punctuations : Pits in the surface of the cuticle, frequently present on the scutum and sometimes present on the basis capituli of some of the hard ticks. The pits may be deep or shallow, small or large. Scapulae Anterior angles or "shoulders'' of the scutum that project on either side (sing, scapula) of the emarginalion. Sclerotized : Hardened in definite areas by deposition or formation of organic or in- organic substances in the cutícula (termed sclerotin). Segment : Distinct articulated entity of a palpus or a leg. Scutum : The sclerotized dorsal plate posterior to the capitulum in hard ticks. It covers almost the entire dorsal surface in the male, about half the dorsal surface in the unen gorged female. (See engorged.) Spiracular plates : Paired plates located ventrolaterally and posterior to coxa IV in hard ticks; may be oval, rounded, or comma-shaped. In the soft ticks the spiracular plates are located ventrolaterally and opposite coxa IV and are usually round or oval. They are the external evidence of the respiratory system.

19 Spurs : Coxal spurs are projections from the posterior surface or posterior mar- gin of the coxae; may be rounded or pointed, small or large. Projections on the median side are called internal spurs ; those on the lateral side are called external spurs. Metatarsal spurs are small, pointed projections on the distal end of the metatarsus. Spurs may also be found on the palps of some species.

Subanal shields : Paired, projecting sclerotized structures on venter posterior to the adanal and accessory shields in males of Hyalomma.

Subapical dorsal The subterminal protuberance present on the tarsus of some species of protuberance : soft ticks. It should be distinguished from the dorsal humps which are present on the tarsus and metatarsus. Subterminal : Before the end, or not quite attaining the end.

Sutural line : Distinct line around the outer margin separating dorsal and ventral surfaces in Argas ticks.

Tampan : A South African term referring to soft ticks, especially Omithodoros and Argas.

Venter : Entire ventral or underside of the body.

Ventral : Pertaining to the underside of the body.

Ventral cornua : Very small projections arising from the posterolateral angles of the ventral surface of the basis capituli.

Ventral plaques : Small, non-projecting sclerotized plates on the venter immediately ante- rior to the festoons in the males of some species of Amblyomma.

Ventral scutes : Chitinous thickenings of the ventral surface of the festoons of Am- blyomma. They may be distinct, protruding, faint, or absent.

XI. KEY TO FAMILIES OF TICKS

Scutum present, short in female, long in Sexual dimorphism is pronounced, the dorsum male. Capitulum at anterior of the male is almost completely covered by the of body in all stages. .Family Ixodidae, p. 21 scutum, and the body is incapable of becoming Scutum absent. Capitulum on underside of greatly enlarged; whereas, the dorsum of the body in nymphs and adults, female is only partially covered by the scutum anterior in larvae... Family Argasidae, p. 29 and the body is capable of considerable enlarge- Family Ixodidae ment. The scutum of the engorged female ap- pears as only a small shield posterior to the Morphological Characteristics capitulum. Poröse areas are present on the of the Family basis capituli of the female, absent on the basis The family Ixodidae, the so-called "hard capüttü of the male. The capitulum is always ticks," includes those ticks that have a scutum. anterior and visible dorsally. The spiracular

20 plates are located posterior and somewhat 6. Palps very short, compressed and ridged lateral to coxa IV. dorsally and laterally. Males with normal legs Genus Boophilus, p. 24 Key to Development Stages of Palps short, but not ridged dorsally and Family ixodidae laterally. Males with massive, beady leg segments Genus Margaropus, p. 28 1. Six legs present Larvae 7. Palps short, second segment not twice as Eight legs present 2 long as wide. Basis capituli rectangular 2. Genital aperture not present (unde- dorsally Genus Dermacentor, p. 25 veloped). Scutum similar to the female Palps long, second segment twice as long type but basis capituli does not have as wide. Basis capituli of variable form, poröse areas Nymphs usually subtriangular or subrectangular Genital aperture present. Scutum of dorsally 8 male or female type. Basis capituli of 8. Eyes absent. (Reptile female with poröse areas Adults parasites Genus Aponomma, p. 23 Eyes present 9 Key to Genera of Adult of Family 9. Scutum usually ornate.^ Festoons well Ixodidae developed. Males without adanal shields, 1. Anal groove distinct and curves around accessory shields and subanal the anus in front. Inornate. Eyes absent. shields Genus Amblyomma, p. 22 Festoons absent Genus Ixodes, p. 27 Scutum inornate. Festoons poorly Anal groove located behind the anus or developed (often coalesced). Males is absent. Ornate or inórate. with adanal shields, accessory shields, Eyes present or absent. Festoons present usually subanal or absent 2 shields Genus Hyalomma, p. 27 2. Second segment of palps projects beyond the lateral margin of the basis capituli. General Comments Eyes absent.. .Genus Haemaphysalts, p. 26 The family Ixodidae is represented in Second segment of palps not projecting North America by seven genera: Amblyomma, beyond the lateral margin of the basis Aponommu, Boophilus, Dermacentor, Haernxjir- capituli. Eyes usually present .3 physalis, Ixodes, and Rhipicephalus. Additional 3. Basis capituli hexagonal (six-sided).^ genera found in other areas of the world in- Usually inornate 4 clude Cosmiomma, Hyalomma, Margaropus, Basis capituli not hexagonal dorsally. and Rhipicentor. The principal hosts of the Ornate or inornate 7 hard ticks are mammals, reptiles, amphibians, 4. Festoons present. Spiracular plate and birds. Generally, only those species known comma-shaped or subtriangular. Coxae to be of economic importance as pests of live- I deeply cleft 5 stock are stressed in this manual. (See charts, iPestoefis ™^bs^it. Spir^acular plate mral. pp. 33-34.) Coxae I not deeply cleft in female 6 5. Males with adanal shields and usually GENUS AMBLYOMMA accessory shields. Coxae IV of male of normal size. Segment 1 of palps without Morphological Characteristics dorsal spur.... Genus Rhipicephalus, p. 28 of the Genus Males without adanal and accessory Palps long, segment 2 at least twice as long shields. Coxae IV of male greatly en- as wide. Generally ornate. Eyes and festoons larged. Segment 1 of palps with dorsal present. Basis capituli of variable form, usually spur Genus Rhipicentor, p. 28 subtriangular or subrectangular dorsally. ^An African species, Rhipicephalus pulchellus, not Adanal shields absent in the male, but small presently established in the United States, is one com- ventral plaques may be present ventrally in mon exception; the male has a rectangular basis capi- tuli and both sexes are ornate. ' Amblyomma inornatum lacks ornamentation.

21 front of the festoons. Ventral scutes may be Scutum with abundant ornamentation in present and extend beyond posterior margin of an extensive pattern 4 the festoons of the male. Spiracular plates sub- 4. Coxa I with the internal spur very short triangular or comma-shaped. or insignificant Amblyomma maculatum Coxa I with the internal spur about half Key to the Males of the the length of the external spur 5 United States 5. Festoons with chitinous tubercles at posterointernal 1. Scutum inornate Amblyomma inornatum angle Amblyomma cajennense Scutum ornate 2 Festoons without chitinous 2. Coxa I with the internal spur tubercles Amblyomma imitator moderately long 3 6. Coxa IV with the external spur longer Coxa I with the internal spur than the internal spur (often difficult to short or insignificant ^ 4 see or may be absent). Common on 3. Scutum with abundant ornate markings, snakes and iguanas imported from South more or less radiating from the center ; America Amblyomma dissimile markings most prevalent in central and Coxa IV with the internal and external anterior area of spurs very small and about equal. scutum Amblyomma cajennense or Found on the gopher-tortoise in the A. imitator "^ coastal plain of Southeastern United Scutum with sparse ornate markings, States Amblyomma tuberculatum usually four or more symmetrically isolated patches ; central area of scutum General Comments without ornate The genus Amblyomma is represented in the markings Amblyomma americanum United States by at least seven species, four of 4. Coxae II, III, and IV each which are commonly found on livestock. Those with one spur Amblyomma maculatum found on livestock include A. americanum, A. Coxae II, III, and IV each with two spurs. .5 cajennense, A. imitator, and A. maculatum. 5. Coxa IV with the external spur distinctly Their distribution is limited usually to the longer than the southeastern or southwestern coastal States. internal spur Amblyomma dissimile The long mouth parts and the color pattern on Coxa IV with both spurs very short the scutum are distinctive characters which aid (internal spur may be difficult in recognition of Amblyomma attacking live- to see) Amblyomma tuberculatmn stock in the United States. Two species, A. dissimile, the iguana tick, and A. tuberculatum, Key to the Females of the the gopher-tortoise tick, as larvae and nymphs, United States have attached to and engorged upon bovines. Adults, however, usually attach only to reptiles 1. Scutum inornate... ,Amblyom7na inornatum and amphibians. The engorged adult A. tuber- Scutum ornate '\ 2 culatum may be almost an inch in length. 2. Coxa I with the external spur distinctly Another species, A. inornatum, has been col- longer than the internal spur 3 lected from dog, cow, coyote, deer, and rabbit in Coxa I with external and internal spurs southern Texas. approximately but not exactly equal 6 Amblyomma americanum, the lone star tick, 3. Scutum with scant ornamentation, so named because of the conspicuous ornate usually limited to a distinct spot near the spot on the posterior of the female scutum, is posterior end . Amblyomma americanum one of the more economically important species. The long mouth parts and great abundance * Differentiation between the male A. cajennense and of this tick make it an especially annoying A, imitator is difficult. The male A. imitator is usually paler, narrower, and smaller. See Kohls' original de- pest of livestock. The wound produced pre- scription of A. imitator for additional information on disposes livestock to attack by the screwworm the separation of the two species. fly, Cocb^iomyia hominivorax.

22 The lone star tick is also important from In Africa members of the genus Amblyomma the public health standpoint because it is are frequently called bont ticks. The word capable of transmitting tularemia, Rocky Moun- **bont" is of Afrikaans origin and refers to the tain spotted fever, and Q fever; and it produces presence of brightly colored patterns on thé tick paralysis in man and dogs. scutum and the white-banded legs. This is an The lone star tick is more widely distributed economically important group of ticks in Africa. in the United States than the other Amblyomma Five species frequently found on livestock are species. It is commonly found from Texas north A. hebraeum, A. variegatum, A. gemma, A. to Missouri and eastward to the Atlantic coast. pomposum, and A. lepidum. A. americanum is a 3-host tick. It may be Amblyomma variegatum, the tropical bont active from early spring to late fall and all tick, was found on cattle on St. Croix, U. S. stages attack livestock and man. Virgin Islands, in August 1967. Subsequently, A. variegatum was also collected from sheep, Amblyomma cajennense, the Cayenne tick, goats, dogs, horses, and mongooses. An eradica- has limited distribution in the United States, tion program started in late 1967 was com- being confined to a few counties in southern pleted by May 1970. In June 1974, A. variegatum Texas. In tropical Central and South America, was found established in Puerto Rico. See this species has been reported abundant, active page 39. the year round and of definite economic im- The tropical bont tick was first reported m portance as a livestock pest. It is a known the Western Hemisphere (Antigua) in 1895. vector of Rocky Mountain spotted fever in Apparently it had been introduced 30 to 40 Mexico, Panama, Colombia, and Brazil. A. years previously with cattle imported from cajennense is a S-host tick. Senegal, located on the west coast of Africa at Amblyomma imitator was, until 1958, con- about the same latitude as Antigua. It spread fused with A. cajennense. The species has been to St. Kitts and Guadeloupe, but it was not recorded from man and a variety of domestic known to exist in the U. S. Virgin Islands and wild animals in southern Texas, Mexico, before August 1967. The tropical bont tick is a and Central America. Its definitive distribution, serious pest of domestic livestock and has a life history, and economic importance have not broad host range. It is a known vector of the yet been determined. virus of Nairobi sheep disease and also trans- mits the agent which causes heartwater in Amblyomma maculatum, the Gulf Coast tick, cattle, sheep, and goats. Neither disease was is an important pest of livestock. The adults found in the U. S. Virgin Islands. are usually found in clusters in the external ear where they produce an intense inflammation. Amblyomma hebraeum, the South African Tick bites predispose the ear to attack by the bont tick, has been reported on several occasions screwworm fly. The Gulf Coast tick is found in the United States on rhinoceroses imported in those States bordering the Gulf of Mexico from South Africa. This is a 3-host tick that and along the Atlantic Coast of South Carolina, transmits the agent which causes heartwater in Georgia, and Florida. This species is rather cattle, sheep, and goats. exacting in its environmental requirements, usually preferring areas of high rainfall, tem- GENUS APONOMMA perature, and humidity. It is seldom found in Morphological Characteristics great number more than 100 to 150 miles from of the Genus the coast.^ Livestock are attacked principally during the late summer and early fall. A, Palps long, segment 2 at least twice as long maculatum is a 3-host tick. The larva and as wide. Ornate or inornate. Eyes absent. nymph generally feed on birds and small Festoons present. Basis capituli rectangular or mammals, while the adult prefers livestock. subrectangular dorsally. The Species of Aponomma ^Established infestations of A, maculatum of live- stock have been reported from at least 15 counties in No key to the species of Aponomma is in- OJcl ahorna. cluded in this manual.

23 General Comments Texas-Mexico border. Periodic reinf estations in The genus Aponomma closely resembles the the quarantine zone occur from adjacent genus Amblyomma except that Aponomma is heavily infested areas of Mexico. smaller in size, broadly oval, and does not have The cattle fever tick, B. annulatus, was eyes. This genus is found almost exclusively on formerly the most common and most economi- reptiles and is of no known veterinary or medi- cally important tick attacking livestock, par- cal importance. Only one species, Aponommxi ticularly cattle, in the Southern States. As a elaphensis Price, is known to be established in vector of Babesia bigemina, the causative agent the United States; it is reported from the of bovine piroplasmosis (cattle fever), this tick Trans-Pecos rat snake in the Big Bend National and the disease it transmits cost the livestock Park, Texas. Other species are occasionally industry an estimated $100 million annually found on snakes and lizards imported from prior to the start of the Tick Eradication Africa and South America. Program in 1906. GENUS BOOPHILUS Boophilus microplus, the tropical cattle tick, was also once established in the United States. Morphological Characteristics It is closely related to J5. annulatus, and the of the Genus females are sometimes difficult to differentiate. Very short, compressed palps, ridged dorsal- Both species are 1-host ticks that prefer ly and laterally. Basis capituli hexagonal dor- similar hosts, and both species are vectors of sally. Eyes present. Inornate. Festoons absent. piroplasmosis and anaplasmosis. As the name Spiracular plate rounded or oval. Male with implies, the tropical cattle tick prefers a adanal shields and accessory shields. Anal tropical or subtropical climate. In the United groove indistinct or absent in female, faint in States, in the past, it was reported most fre- male. Caudal process present or absent in male. quently from Florida and extreme southern Texas. The tropical cattle tick is very prevalent Key to the Males of North America in the more humid and hotter parts of the West With caudal process at posterior extremity Indies, Central America, Mexico, South Amer- of body B. microplus ica, Australia, Africa, and the Orient. Without caudal process B. annulatus Boophilus decoloratus, an African species closely related to B. microplus, has been found Key to the Females of North America " on wild animals from Africa held in quarantine With internal and external spurs of coxa I before being released for entry into the United broadly rounded and wider than long. Coxae II States. In South Africa this is one of the and III with external spurs broadly rounded commonest species parasitizing cattle and less and wider than long. Coxa IV with or without frequently horses. The biology and disease re- a very small external spur.. Boophilus microplus lationships are similar to those of B. microplus. Internal spur of coxa I absent, external spur broadly rounded and wider than long. Coxae GENUS DERMACENTOR II, III and IV without external spurs B. annulatus Morphological Characteristics of the Genus General Comments Ticks of the genus Boophilus have been Basis capituli rectangular dorsally. Eyes and eradicated from the United States—except for festoons present. Palps short, broad, or moder- a small, narrow quarantine zone along the ate. Coxae I to IV of males increase progres- sively in size; in all species coxa IV is the 'Females of some populations are very difficult to largest. Male without ventral plates or shields. separate due to morphological variation. Accurate Coxa I bifid in both sexes. Spiracular plates identification is best accomplished with male specimens. sub-oval or comma-shaped. Usually ornate.

24 Key to the Adults of the United States 7. Spiracular plate with goblets very small 1. Spurs on coxa I widely divergent 2 and numerous (like grains Spurs on coxa I not divergent or only of sand) Dermacentor variabilis slightly divergent 4 Spiracular plate with goblets moderate in size and number 8 2. Scutum inornate. Spiracular plate with- out dorsal prolongation and with few 8. The larger punctations on scutum very (usually 4-10), large, isolated goblets. large and deep Dermacentor andersoni Seven festoons present (not distinct on (=D. venustus) engorged female) Dermacentor rdtens The larger punctations on scutum moder- (=Anocentor nitens) ate in size and depth. From bighorn Scutum ornate. Spiracular plate with sheep in Arizona and dorsal prolongation and with many Mexico Dermacentor hunteri small or medium sized goblets. Eleven festoons present 3 General Comments 3. Scutum with large, deep punctations. The genus Dermacentor comprises an im- Cervical grooves of female deep and portant group of ticks in the United States, extend nearly half the length of scutum. particularly as vectors of disease-producing (Primarily a rabbit tick of the South- organisms affecting man. Several of the species western United States and adjacent area are known transmitters of Rocky Mountain of Mexico) . .. .Dermacentor parumapertus spotted fever, tularemia, Colorado tick fever, Scutum with the punctations shallow and Q fever; some species may produce tick and moderate in size. Cervical grooves paralysis. Several members of this genus are of female deep and short, scarcely more also important pests of livestock, both as disease than pits. Found on peccary (javelina) vectors and as bloodsucking parasites. in Texas and Mexico Dermacentor halli This genus is represented in the United 4. Spiracular plate without dorsal pro- States by at least nine species, six of which longation ^ and with goblets of medium commonly attack livestock. D. andersoni (= D. size and number 5 venv^tus), D. occidentalis, and D. variabilis are Spiracular plate with dorsal prolongation 3-host ticks. Dermacentor albipictus and the and with goblets many or of moderate closely related D, nigrolineatus, as well as D. numbers 6 nitens, are 1-host ticks. The three additional 5. Scutum and legs profusely species Z>. halli, D. hunteri, and D. parumapertus covered with white do not commonly attack livestock. ornamentation Dermacentor albipictus Dermacentor nitens (= Anocentor nitens), Scutum without white or with very little the tropical horse tick, is an important parasite white ornamentation. Common on deer of horses, mules, and asses in parts of Mexico, in Southeastern United States Central America, and the West Indies. Until of America Dermacentor nigrolineatus about 1960, it was believed the tropical horse 6. Cornua long, especially in the male tick was established in the United States only (found along Pacific Coast of California in extreme southern Texas. Evidence now in- and Oregon) Dermacentor occidentalis dicates that this species is also well established Cornua short or of moderate length 7 in southern Florida. Dermacentor nitens is a 1-host tick. It is usually found in the ears of ^ The frame of the spiracular plate of some specimens horses, mules, and asses, although it has also of D. albipictus is occasionally formed to resemble a been found on cattle, goats, and deer. In heavy partially developed dorsal prolongation. When such a specimen is encountered, one may possibly identify it infestations on horses, it has also been found as D, hunteri with this key. However, the dorsal pro- in the nasal diverticulae, the mane, the perineal longation is very definite in D. hunteri. region, and along the ventral midline.

25 Dermacentor albipicttis, the winter tick, is an Rocky Mountain wood tick, is one of the most important pest of horses, cattle, moose, elk, and infamous transmitters of diseases of man in deer in the northern and western United States. the United States. It is a vector of Rocky It is often abundant on range stock and, if not Mountain spotted fever, tularemia, Colorado controlled, may cause losses through weakened tick fever, and Q fever; and produces tick condition or death of the host. This 1-host paralysis in both man and animals. It is also tick is active during the late fall, winter, and a suspected vector of anaplasmosis in cattle. This early spring. species has been reported in 14 Northwestern Dermacentor nigrolineatus, the brown winter States and in three provinces of southwestern tick, is closely related to D. albipictus. In fact, Canada. It is a 3-host tick. The nymph and some taxonomists regard D. nigrolineatus as a larva feed primarily on small animals, such as variation or "form" of D. albipictus. Other squirrels, chipmunks, and rabbits ; whereas, the authorities regard the completely inornate D. adults generally attack the larger mammals— nigrolineatus as a valid species. horses, cattle, sheep, deer, and man. The brown winter tick is widely scattered throughout the eastern half of the United GENUS HAEMAPHYSALIS States, both north and south, although the inci- Morphological Characteristics dence of this species is greater in the south- of the Genus eastern quarter of the country. In southwestern Texas and New Mexico, the distribution of D. Inornate. Eyes absent. Festoons present. albipictus and D, nigrolineatus may have over- Usually short conical palps with second seg- lapped with a crossing of the two species re- ment projecting beyond the lateral margin of sulting in a fertile hybrid which is sometimes the basis capituli which is rectangular in the difficult to place in either species. The pre- dorsal view. Usually of small size and sexual ferred host for the brown winter tick in the dimorphism slight. Ventral plates or shields southeastern states is the white-tailed deer, absent in the male. Posterior margin of coxa although it will also attack horses, mules, and I never bifid or deeply cleft. Spiracular plates cattle. It is a l~host tick and is found on usually rounded or comma-shaped in the male, animals only during fall, winter, and spring. rounded or oval in the female. Dermacentor occidentalis, the Pacific Coast Key to the Adults tick, is common from Oregon to lower Cali- of the United States fornia. This species occurs on a variety of Ventral cornua present. Dentition of domestic animals with occasional heavy infesta- hypostome 3/3. ,Haemaphysalis leporispalustris tions on deer. Adult ticks are most numerous Ventral cornua absent. Dentition of on hosts during the rainy season. All stages of hypostome 5/5 H, chordeilis the tick have been reported on cattle. This is a 3-host tick. General Comments Dermacentor variabilis, the American dog The genus Haemaphysalis includes approxi- tick, is widely distributed in the United States. mately 150 species. Only two species, H. It is found in all the States east of the Rocky leporispalustris and H. chordeilis, are known to Mountains, as well as in California, Washing- be established in the United States. Neither is ton, Idaho, and Oregon. The American dog tick commonly found on livestock. Both species are is an important vector of Rocky Mountain 3-host ticks. spotted fever in the Eastern States. It transmits Haemaphysalis leporispalustris, the rabbit tularemia and possibly bovine anaplasmosis tick, is widely distributed in the United States and produces tick paralysis. D. variabilis is from Massachusetts to California. The adult a 3-host tick. Although the dog is the preferred is found primarily on rabbits and ground- host for the adult tick, man, as well as domestic frequenting birds; whereas, the larva and and wild animals, is frequently attacked. The nymph are usually found on numerous kinds larva and nymph prefer small rodents, espe- of birds and small mammals. None of the stages cially mice, rats, and rabbits. are commonly found on livestock or man. This Dermacentor andersoni (= D. venustus), the species may be more important than is realized.

26 Evidence indicates that the rabbit tick may be established. The species of this genus are espe- an important factor in the spread of Rocky cially eflScient vectors of a variety of disease- Mountain spotted fever and tularemia among producing organisms of man and animals. wild animal reservoir hosts. Hyalomma ticks are probably among the most Haemaphysalis chordeilis, the bird tick, is economically important external parasites which also widely distributed in the United States. attack animals. Birds are the preferred hosts for all stages of the species, and livestock and man are only GENUS IXODES rarely attacked. Several authorities have re- Morphological Characteristics ported deaths in turkeys and wild game birds of the Genus from heavy infestations of this species. Some important species of Haemaphysalis in Anal groove distinct and curves around the other areas of the world are H. leachi of Africa, anus anteriorly, and usually uniting in a point H. longicornis of Australia, New Zealand and or arch. Inornate. Eyes and festoons absent. Japan; and H, bispinosa of Ceylon, Pakistan, Palps and basis capituli of variable form. India, and Malaysia. Spiracular plates round or oval. Venter of male covered with seven nonprojecting, armor-like GENUS HYALOMMA plates. Sexual dimorphism pronounced, espe- Morphological Characteristics cially in regard to the capitulum. of the Genus The Species of Ixodes Ornamentation, if present, limited to pale bands on legs. Eyes present. Festoons irregular, Due to the complexity of the ticks in this partially coalesced. Palps long, segment 2 ap- genus, no attempt has been made to present a proximately twice as long as segment 3. Basis key for the identification of the species. It is suggested that all Ixodes be referred to a capituli subtriangular dorsally. Coxa I usually deeply cleft. The male with adanal and acces- specialist for identification. For information on the identification and distribution of the species 90Yy shields and usually subanal shields. in the United States, refer to Cooley and Spiracular plate usually comma-shaped. Kohls (1945). The Species of Hyalomma General Comments No key to the species of Hyalomma is in- cluded. All suspected specimens of Hyalomma Some 200 species of the genus Ixodes are ticks should, without exception, be forwarded found throughout the world. Over 30 species to the Veterinary Services Laboratories for have been reported in the United States. Only identification or confirmation. two species, however, /. pacificus and /. scapu- laris, are commonly found on livestock in the General Comments United States ; both are 3-host ticks. The long Until relatively recently the taxonomic status mouth parts of the female Ixodes enable these of the species in the genus Hyalomma was con- ticks to be especially painful and annoying fused. However, thanks to Hoogstraal and parasites of livestock and man. Kaiser, this group is now reasonably well Ixodes pacificus, the California black-legged understood. The Hyalomma complex of species, tick, is commonly found on domestic livestock, which at one time consisted of almost 100 deer, and man along the western coast of the species or subspecies, is now recognized as con- United States from Me^tico to British Columbia. sisting of approximately two dozen or fewer Records indicate that this species is most valid species. abundant on livestock during the spring. Fortunately, the genus Hyalomma is not rep- Ixodes scapularisy the black-legged tick, is resented in the New World. It is distributed found primarily from Texas and Oklahoma throughout Asia, Africa, and southern Europe. eastward to the Atlantic Ocean, but it has been Adult Hyalomma ticks are primarily parasites reported as far north as Minnesota and Wis- of domestic animals and are of considerable consin and as far northeast as southern Massa- economic importance in areas where they are chusetts. In the Southern States, where this

27 species is commonly found, it is abundant in plates subtriangular or comma-shaped. The winter and early spring. This tick is not known male resembles Rhipicephalus dorsally, Derma^ to naturally transmit livestock diseases ; it is a centor ventrally; coxa IV is greatly enlarged; suspected vector of anaplasmosis and tularemia. adanal shields and accessory shields absent. All Also, see footnote on p. 51. coxae with a well developed antero-external Other important species of Ixodes are /. prolongation which is spurlike in coxa I. Coxal ricinus of Europe, /. persnlcatus of parts of spurs are sharper than in Rhipicephalus. Asia and parts of Europe, /. holocyclus of Australia, and /. rubicundus of southern Africa. The Species of Rhipicentor No key to the species is included in this GENUS MARGAROPUS manual. See Theiler (1961). Morphological Characteristics of the Genus General Comments Palps short but not ridged as in Boophilus. The genus Rhipicentor presently contains two Basis capituli hexagonal dorsally. Eyes present. species and both are established only in Africa. Inornate. Festoons absent. Legs of male in- Rhipicentor hicornis has been reported from crease progressively in size from pair I to IV ; goats, horses, cattle, dogs, and wild carnivores the segements of leg IV greatly enlarged. Male in southern and central Africa. The biology with adanal and sometimes accessory shields. and disease relationships are unstudied, but Spiracular plates rounded or oval in both sexes. since it does parasitize domestic animals it is Anal groove absent or indistinct. potentially dangerous. Rhipicentor nuttalli has been reported from hedgehogs, dogs, hyenas, The Species of Margaropus wild cats, large carnivores, and cattle in sou- thern Africa. No key to the species is included in this manual. See Hoogstraal (1956). GENUS RHIPICEPHALUS General Comments Morphological Characteristics of the Genus The genus Margaropus is closely related to Boophilus and is known to be established only Palps short and basis capituli usually hexa- in Africa. At one time Boophilus annvlatus was gonal dorsally. Usually inornate. Eyes and placed in the genus Margaropus, and much of festoons present. Coxa I deeply cleft. Males the older literature lists B. annulatus as with adanal shields and usually accessory Margaropus annulatus. shields. Spiracular plates comma-shaped. Cau- Only two species, M. winthemi and M. reidi dal process present or absent in male. are presently included in this genus. Margaropus The Species of Rhipicephalus ivinthemi is found in southern Africa and feeds chiefly on horses and cattle ; it is a 1-host tick Due to the number, complexity, and economic and the female resembles B. decoloratus, but is importance of the species in the genus Rhipi- larger. Margaropus reidi is reported only from cephalus, no key is included in this manual. the giraffe in the western Sudan; the biology All Rhipicephalus ticks should be submitted to and disease relations are unstudied. the Veterinary Service Laboiatories, Beltsville, Md., for identification or confirmation. GENUS RHIPICENTOR General Comments Morphological Characteristics of the Genus The genus Rhipicephalus apparently origi- nated in Africa where some 60 species are now Inornate. Eyes present. Festoons present. found. These ticks are especially important as Basis capituli hexagonal dorsally. Palps short; reservoirs and vectors of a variety of animal segment 1 with a short broad dorsal spur. Coxa diseases. Some of the economically im- I unusually long and deeply cleft. Spiracular portant diseases transmitted or produced by 28 Rhipicephalus ticks include piroplasmosis, Key to Genera of Family Argasidae anaplasmosis, theileriosis, tick toxicosis, and spirochetosîs. 1. Margin of body thin and acute with a definite sutural line separating the At least three species of Rhipicephalus, dorsal and ventral namely R. evertsi, R. pulchellus, and R. appert- surfaces Genus Argas, p. 30 diculatus, are occasionally found on zoo-type Margin of body thick, rounded, and animals being held in quarantine at the USDA without a definite sutural line separating Animal Import Center at Clifton, N.J. Other the dorsal and ventral surfaces .2 important species in Africa are R. capensis, R. pravus, and R. simus. 2. Integument of nymph covered with spines. Adult with granular integument At the present time, R. sanguineus is the only and poorly developed species of this genus established in the United hypostome Genus Otobius, p. 31 States. However, in 1960 R. evertsi, the red- Integument of nymph and adult mam- legged tick, was found on a variety of zoo millated and without spines. Adult animals in two wild animal compounds in with well-developed Florida and a game farm in New York. Based hypostome Genus Ornithodoros, p. 30 on the degree of infestation and number of animals infested, the red-legged tick had been General Comments established in one of the zoological compounds in Florida for approximately 2 or 8 years. The family Argasidae is represented in the Following an intensive eradication program, United States by four genera, three of which the red-legged tick was eliminated from the have been found on livestock and poultry— United States by 1961. Argas, Otobius, and Ornithodoros. The fourth genus, Antricola, has been found in bat guano and is suspected of feeding on bats. Family Argasidae The Argas persicns complex of species, Morphological Characteristics although not presently of much economic im- of the Family portance, was once a serious pest of domestic fowl in Florida and several Southwestern The family Argasidae, "soft ticks," consists States. The spinose ear tick, Otobius megnini, of those ticks that lack a scutum. Sexual is the only soft tick commonly found on live- dimorphism is not marked ; the males closely stock in the United States. Ticks of the genus resemble the females. Poröse areas are absent. Ornithodoros are not usually important para- The capitulum of the nymphs and adults is sites of livestock, although several species are always ventral and not visible dorsally, except important vectors of the spirochetes of relapsing for the distal end of the palps, which sometimes fever in man. The principal host of the soft project beyond the anterior margin of the ticks include birds, rodents, and bats—occas- body. The capitulum is anterior in the larvae. ionally livestock and man. (See chart on p. 35). The spiracular plates usually are located The South Africans commonly refer to most anterior to coxa IV. soft ticks as tampans, but this term has not gained acceptance in the United States. Key to Development Stages of Fam^ily Argasidae GENUS ARGAS 1. Six legs present Larvae Morphological Characteristics Eight legs present 2 of the Genus 2. Genital aperture undeveloped; in large Body distinctly flattened with dorsal and nymphs may appear as a small ventral surfaces approximately equal in area. depression Nymphs Margin of body flattened and composed of radial Genital aperture well developed.. Adults striae or quadrangular plates. Sutural line

29 present. Integument leathery, minutely wrinkled Key to the Adults in folds, often intermingled with small, rounded Most Commonly Found on Livestock "buttons," each with a pit on top and often in the United States bearing a hair in the pit. Eyes absent. Sexes 1. Cheeks present Ornithodoros talaje similar. Nymphs and adults similar. Cheeks absent 2 The Species of Argas 2. Eyes present (on sides of body above Due to the complexity of this genus, no key second and third coxae). Tarsus IV is included to separate the species of Argas. with prominent subapical dorsal pro- See Kohls ei aï (1970). tuberance. (Reported from Pacific General Comtnenis Coast of California and Mexico) Ornithodoros coriaceus It has been found that the ticks commonly Eyes absent. Tarsus of leg IV without identified as Argas persicus in the United subapical dorsal States actually represent a complex of species. protuberance Ornithodoros turicata The true A. persicus, an Old World species, is apparently rather rare in the New World. The General Comments common Argas species found in the United This genus is well represented in the United States are A. radiatns and A. sanchezi; a fourth States, especially in the Southwestern and species. A, miniatus, may also occur, but definite Western States, with some 15 species being proof of its presence is still lacking. These four reported. Several species occasionally attack closely related species have been reported from livestock, but generally Ornithodoros ticks are domestic poultry in the New World. Argas not a problem as pests of domesticated animals. radiatns and A. sanchezi have also been found This genus is primarily significant as the vector on various wild birds. Three additional species, of spirochetes of relapsing fever in man. A. brevipes, A. cooleyi, and A. giganteus, have Ornithodoros turicata, the relapsing fever been reported from or associated with wild tick, and 0. talaje, which has no common name, birds in the western United States. The genus occasionally attack domestic animals in the Argas is of little economic importance as pests United States. These species have been reported of livestock in the United States. from the Southwestern States and Florida. They are not known to be vectors of livestock GENUS ORNITHODOROS diseases, but are vectors of relapsing fever in Morphological Characteristics man in the Southwestern States. of the Genus O. coriaceus, the pajaroello tick, has been Capitulum either subterminal or distant from taken from cattle and deer in California and anterior margin. Hypostome well developed and the Pacific Coast region of Mexico. It readily essentially alike in both adult sexes and in attacks man and its venomous "bite" is said to nymphs. Integument with discs and mammillae be very painful. This tick, however, is not commingling in a variety of patterns. Hood, known to be a disease vector. camerostome, and checks present or absent. In other areas of the world, particularly Eyes present or absent. Dorsal humps and Africa and Asia, Ornithodoros ticks are im- subapical dorsal protuberances on legs progres- portant as reservoirs and vectors of disease- sively more prominent in successive nymphal producing organisms of man and animals. Some stages. Body more or less flattened but strongly of these species are O. erraticus of northern convex dorsally when distended. Integumental Africa, Portugal, and Spain, O. tholozani of pattern continuous over sides from dorsal to central Asia, O. savignyi of Africa and Asia, ventral surfaces. and the O. moubata species complex of Africa.

30 GENUS OTOBIUS General Comments Morphological Characteristics of the Genus The genus Otohius presently contains only two species, 0. megnini and O. lagophilits, both Integument of nymph covered with spines. of which are found in the United States. The Integument of adult granulated. Sexes similar. spinose ear tick, O. megnini, is a common and Capitulum distant from the anterior margin in adults, near the margin in nymphs. Hood and important pest in the Southwestern States. It is primarily reported from livestock, particu- eyes absent. Hypostome well developed in nymphs, vestigial in adults. larly cattle and horses, although other domestic and wild animals are attacked. The larval and Key to the Nymphs nymphal stages are found in the ears. The nymph is easily recognizable by the spines on Integument with numerous heavy spines the integument and the violin-like shape of the anteriorly and lighter spines posteriorly. body. The adult stage of O. megnini differs Dentition of hypostome 4/4. Spiracles from the nymphal stages in that the integument conical O. megnini lacks spines ; the hypostome is poorly developed, Integument with numerous spines all of and it does not feed. one size. Dentition of hypostome 3/3. Spiracles convex O. lagophilm The spinose ear tick is the only species of Otobiiis reported from livestock. Otohius lago- philus is found on rabbits in the western United Key to the Adults ^ States, Mexico, and Alberta, Canada. Like 0. Pits on dorsal surface of body separated megnini, the adults of 0. lagophilus are not by a distance of two or more times the parasitic. diameter of one pit Otohius megnini Pits on the dorsal surface of body sep- arated by a distance of the diameter or less of one pit O. lagophilus

• The adults are not parasitic and are not likely to be found on animals.

XII. COLLECTING AND PRESERVING TICKS

Finding ticks on an animal often requires well as the eyes, for often a tick that cannot careful examination of all parts of the animal. be seen may be felt. If possible, watch a trained Some species of ticks, such as the spinose ear tick inspector at work and note how carefully tick, tropical horse tick, and the larval and he moves his fingers over an animal. nymphal stages of the red-legged tick, are Female ticks, ordinarily much larger than the almost always attached in the ear of the host. males, are easy to find. Careful scrutiny of the Other species prefer the thin skin between the area near the female tick frequently will also hind legs, under the base of the tail, or on the reveal a tiny male tick. brisket. Some ticks have been collected from Remove ticks from the host carefully so as the eyelids and the tongues of animals. In in- not to break off the capitulum (false head) — specting an animal for ticks, use the fingers as especially in removing ticks with long mouth-

31 parts such as Ixodes and Amblyomma species. Ticks from different species of hosts should Forceps are useful to grasp the tick near the never be mixed. For example, ticks collected head end and "tease" it off. Ticks with short from cattle should not be mixed with ticks mouthparts, as in the cattle fever tick, are collected from horses, even when collected on readily removed without injury. the same farm or ranch. Ticks often may be collected from grass and Any additional information is valuable in other vegetation, where they are awaiting a determining the distribution of a species of host, by dragging a flannel cloth over the area. tick. For example, "Four ticks were collected This procedure is referred to as "dragging" or from inside ear and two ticks from between "flagging" for ticks. The drag is made by hind legs of a young Hereford cow. Animal attaching one end of the flannel cloth (about pastured in dense woodland and only 1 in herd 30" X 60") to a piece of wood, such as a of 20 found to be infested. This animal was broomstick, to which a strong cord is attached purchased about 1 month ago from Paul Cannon for a towline. at Coleman, Texas." For use in brush or scrub, Stampa's modifi- Where to Submit Ticks for Identification or cation of the drag or flag is recommended. The Confirmation—All suspected cattle fever ticks drag is cut into tails, slightly weighted, so that and other exotic species should be forwarded they will fall between the higher twigs and for confirmation and cataloging through the come into contact with the inner parts of the area Veterinarian in Charge to ; brush where the ticks are often found. Blood tubes or screwcap vials are satisfactory containers for tick specimens. Cattle fever ticks Veterinary Services Laboratories and other disease vectors should be put in vials APHIS, USDA containing a preserving fluid before removal from an infested property. Tick specimens can Parasitology Laboratory be preserved in 70 percent isopropyl alcohol Bldg. 322, BARC-East (rubbing alcohol). Beltsville, Maryland 20705

Each tick or group of ticks collected from an animal should be properly labeled, and if possible, should always include at least the following information :

(1) Type animal from which specimen (s) taken Cow, Hereford (2) Geographical location where ticks are collected Hamlin, Jones County, Texas (city, county, and State). (3) Owner's name and address ^ D. W. Scott (4) Number of specimens 7 ticks (5) Collector's name B. F. Hall (6) Date collected October 21, 1974

" This may not always be the same as (2).

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35 XIV. LIFE HISTORY SUMMARIES OF SELECTED TICKS OF VETERINARY IMPORTANCE

The data presented in each of the following LOCATION ON HOST life history summaries was collected from a On livestock, all stages of this tick prefer number of sources. The intent is to present a attachment to thin-skinned areas such as the picture of possible tick development for selected ears, dewlap, escutcheon, axillary region, and species of ticks. A tick may not necessarily inguinal region ; however, in heavy infestations complete all stages of the life cycle within the they may be found attached all over the body. period of time given in the life history sum- mary. The life history summaries indicate the SEASONAL ACTIVITY wide range of variation which may be pos- sible with a given species of tick. This infor- The Lone Star tick is most commonly found mation was obtained in the laboratory or under on livestock in the spring and summer. In the simulated field conditions and does not neces- lower Southern States all parasitic stages have sarily indicate the rate of development under been taken on hosts throughout the year. natural field conditions. LIFE CYCLE SUMMARY Assuming that the relative humidity and precipitation are adequate for survival, tem- The following life history information is perature is the most important factor affecting adapted from Hooker, Bishopp, and Wood: the length of the life cycle. Generally, the Amblyomma americanum is a 3-host tick. parasitic period for each species is relatively The female lays up to 8,300 eggs constant in length, but the nonparasitic period Preoviposition period 5-13 days is often highly variable. The lower the tem- Oviposition period 7-23 days perature is, the longer it takes a tick to go Incubation of eggs 23-117 days through the nonparasitic period. For instance, Larvae engorge 3-9 days the life cycle of Haemaphysalis leporispalustris Larvae molt 8-26 days can be expected to take longer in northern Nymphs engorge 3-8 days Pennsylvania than in southern Texas. Nymphs molt 13-46 days Females engorge 9-24 days Unfed larvae survive up to 279 days Anthlyomma americanum (Linnaeus), Unfed nymphs survive up to 476 days the Lone Star tick Unfed adults survive up to 430 days

DISTRIBUTION ECONOMIC IMPORTANCE This tick is distributed from central and The long mouth parts, capable of deep pene- eastern Texas, north into Missouri, and east in tration, make the bite of this tick painful to a broad belt to the Atlantic coast. It has also man and animals. Suppurating sores form at been reported in Mexico, Guatemala, Guyana, the site of attachment inside the ears and and French Guiana. attract screwworms. Chickens are killed by massive infestations of tick larvae. HOSTS Amblyomma americanum is a carrier of the rickettsia, Coxiella burneti, causative agent of This species has a wide host range. The Q fever. Man and animals are infected by the adults are commonly found on large mammals feeding of ticks or by inhalation of contami- such as cattle, horses, deer, and dogs. Although nated dusts and infected tick feces. This tick the larvae and nymphs attach to the same is also a vector to man of Rocky Mountain hosts as the adults, they prefer to feed on spotted fever and tularemia. In the Eastern and birds and small mammals. All three parasitic Soirtbeni Statei^ A. americanum reportedly stages attack man. causes tick paralysis in man and in dogs. 36 Amblyomma cajennense (Fabricius), Females engorge .7-12 days the Cayenne tick Unfed larvae survive 57-386 days Unfed nymphs survive, .more than 13.5 months DISTRIBUTION Unfed adults survive up to 466 days In the United States, A, cajennense is limited to several counties in southern Texas. This ECONOMIC IMPORTANCE species is widespread throughout Mexico and Amblyomma cajennense is a very serious pest Central America and is also found in the Carib- of man and animals. In parts of South America, bean area and in parts of South America. The it is alleged to cause great damage to cattle by tick derives its name from the locality, Cayenne, producing *'fever," weakness, and death. French Guiana, in v^hich it v^as first collected. This species is a vector of spotted fever in Mexico, Panama, Colombia, and Brazil. Experi- HOSTS mentally, this tick is capable of transmitting All stages of this species attach to man as brucellosis. It is also reported to be capable of well as to livestock. Adults occur in great abun- stage-to-stage transmission of Q fever and has dance on horses, mules, donkeys, cattle, dogs, been experimentally infected with Trypanosoma and a variety of other animals. In many parts cruzi. of tropical America, the larvae and nymphs are extremely abundant and aggressive in Amblyomma hebraeum. Koch, attacking man. the Bont tick LOCATION ON HOST DISTRIBUTION Adult ticks prefer to attach between the legs or on the abdomen. However, in the equine, all Amblyomma hebraeum is a native of southern stages of the tick are frequently found inside Africa. It is found in the Republic of South the ears and in other natural cavities, as well Africa in the coastal areas east of Fort Eliza- as on the flanks, withers, mane, and tail. beth, up through Natal and Zululand into the In cattle, the tick may be found attached to eastern and northern Transvaal; and in parts any part of the body. This species also has of Mozambique, Botswana, and Rhodesia. It been found attached to the tongues of young thrives in a warm, moderately humid climate calves. on the veld where tall grass and trees provide shade. SEASONAL ACTIVITY The bont tick has been found in the United States on several occasions, either on rhino- All stages are found on hosts throughout the ceroses offered for entry or on rhinoceroses year in areas where this species is established. which had recently been imported. For example, in June 1966, two rhinoceroses arrived at the LIFE CYCLE SUMMARY port of Mobile, Ala., enroute to a zoological The following life history information is garden in California. They were trucked from adapted from Hooker, Bishopp, and Wood : Mobile prior to treatment. Veterinary Services Amblyomma cajennense is a 3-host tick. inspectors at Laredo, Tex., learned that the The female lays up to 7,700 eggs animals had been held for feed, water, and rest Preoviposition period 9-20 days in Laredo. They collected ticks which were Oviposition period average 19.7 days later identified as A, hebraeum. Meanwhile, the Incubation of eggs 37-154 days truck proceeded to El Centro, Calif., where the Larvae engorge 3-7 days rhinoroses were treated prior to proceeding Larvae molt approximately 10 days to destination. The animals were heavily in- Nymphs engorge 3-13 days fested with A. hebraeum at the time of treat- Nymph molt 12-105 days ment.

37 HOSTS ECONOMIC IMPORTANCE Cattle and antelopes are the preferred hosts The bont tick is a vector of Cowdria rumi- for the adult ticks but a variety of larger nantium, causative agent of heartwater in cattle, domesticated and wild mammals are attacked. sheep, and goats. Rickettsia conori, which pro- The larvae and nymphs also feed on the larger duces boutonneuse fever (tick typhus), has mammals as well as on a number of smaller been isolated from this species and it is ap- ones, particularly wild hares. The immature parently a vector in the South African veld. stages frequently feed on ground birds and The long mouth parts of A. hebraeum enable even reptiles. it to produce deep-seated, painful wounds which often become infected and lead to abscess LOCATION ON HOST formation and infestation with blowfly larvae. The adults prefer bare areas of the body, When these ticks occur on the legs and between especially under the tail, on the genitals, teats, the toes of cattle and sheep, they may cause udder, and in the groins and axillae. They are sores that result in lameness. also found on the dewlap, brisket, and under- sides of the abdomen. Larvae and nymphs Amblyomma maculatum Koch, attach anywhere on the body. the Gulf Coast tick

SEASONAL ACTIVITY DISTRIBUTION In South Africa, the adults are most abun- dant on hosts during the late summer and In the United States, thi« tick is found pri- autumn months. marily in the Southern States bordering the Gulf of Mexico and along the Atlantic coast. It LIFE CYCLE SUMMARY is seldom established more than 200 miles inland. However, Veterinary Services personnel The following information is adapted from have found established infestations on sheep Lounsbury and from Nuttall : and cattle in several counties in northeastern Amblyomma hebraeum is a 3-host tick. Oklahoma. The tick has also been reported The female from Mexico and several countries in northern lays 10,000-20,000 eggs South America (Colombia, Ecuador, Vene- Preoviposition period 2-11 weeks zuela) . Oviposition period 3-9 weeks Incubation of eggs 11 weeks-6 months HOSTS Larvae engorge 4-9 days The larvae and nymphs engorge primarily on Larvae molt 16 days-3 months ground-inhabiting birds, although they are also Nymphs engorge 4-8 days found on small mammals. Sheep, mules, horses, Nymphs molt 18 days-11 weeks cattle, dogs, and deer are common hosts for Females engorge 6-10 days adult ticks. Man is sometimes attacked by the Total 147 days-409 days adults. Unfed larvae survive up to 346 days Unfed nymphs survive up to 250 days Unfed adults survive more than 660 days LOCATION ON HOST The larvae and nymphs are found primarily In South Africa, at least 9 months are re- on the head and neck of birds, and on the head quired to complete the life cycle under natural and ears of small mammals. The adults prefer conditions; in exceptional circumstances 2 to attach to the head, particularly the ears, of years or more may be required. Normally, how- larger mammals, but in heavy infestations may ever, one generation is completed each year. also%e found efi other areas.^ the^ body.

38 SEASONAL ACTIVITY Amblyomma variegatum (Fabrîcîus), The imature stages are found on birds the Tropical Bont tick throughout the year but are most abundant in the spring and summer. The adults are found on DISTRIBUTION livestock in the greatest numbers during the The tropical bont tick is a native of Africa late summer and early fall. and is widely distributed in Eastern, Central, and Western Africa. It was introduced into the West Indies in the mid-to-late 1800's on cattle LIFE CYCLE SUMMARY imported from Senegal and is now well The following information is adapted from established on St. Kitts, Guadeloupe, and Hooker, Bishopp, and Wood ; and Bishopp and Antigua. Hixon: In September 1967, A, variegatum was found Amblyomma maculatum is a 3-host tick. established on St. Croix, U.S. Virgin Islands. An extensive program of inspection, dipping, The female lays up to 18,000 eggs and ground spraying was carried out, and by Preoviposition period 3-9 days May 1970, the tropical bont tick had been Oviposition period 13-75 days eliminated from St. Croix. Incubation of the eggs 21-142 days In June 1974, A. variegatum was confirmed Larvae engorge 3-7 days as being established in Puerto Rico. Subsequent Larvae molt 7-121 days investigations revealed the presence of the tropi- Nymphs engorge 5-11 days cal bont tick on at least 26 premises in the area Nymphs molt 17-71 days of Cidra and Cayey, some 25 miles south of San Juan. Females engorge. 14-18 days Unfed larvae survive up to 179 days Unfed nymphs survive somewhat longer HOSTS than larvae The common hosts for adult ticks include Unfed adults survive up to 411 days cattle, sheep, horses, goats, antelopes, camels, Due to the limited seasonal activity of the and a long list of large wild mammals. Man adult stage, the Gulf Coast tick probably com- has also been reported as a host for the adult pletes one life cycle per year under normal stage. Nymphs feed on a great variety of conditions. mammals of medium and large size, occasionally including man. Birds are frequently attacked by the nymphs. The larvae may feed on any of ECONOMIC IMPORTANCE these hosts but prefer smaller mammals and birds. The Gulf Coast tick has been incriminated as a producer of tick paralysis in man and dogs in the Southeastern United States. LOCATION ON HOST This tick causes "tick worry" to domestic The adult ticks are commonly found on the animals and massive infestations result in lower part of the dewlap, brisket, axillae, great loss of blood, debilitation, and even death. abdomen, groins, escutcheon, udder, and ex- Heavy infestation of the ears often results in ternal genitalia of the male. They may also be the development of a condition suitable for found on or near the vulva, under the tail, and attack by the screwworm, Cochliomyia homini- in the interdigital cleft. The immature stages VOTUX. are more likely to attach anywhere on the host.

119 SEASONAL ACTIVITY The bite of the adult tropical bont tick is The following information is taken from especially serious since the mouth parts pene- Hoogstraal (1956) and applies to the Sudan: trate very deep, resulting in the formation of "Adults appear towards the end of the dry wounds and abscesses. Severe lameness may be season, first males and then females. Popula- caused by the attachment of the ticks in the tions increase in numbers and remain high interdigital clefts. A definite reduction in the through the rainy season and decrease rapidly value of hides and skins is caused by heavy in the dry season, although a few specimens infestations of A. variegatum. may be found even then. Larvae and nymphs In some areas the larvae are a serious pest of gradually become more numerous in the dry man and attach on the legs and around the season, and while some nymphs are found waist. Larvae reportedly may burrow under the during the rains they are scarce." skin and cause intense irritation and inflam- mation. The causative agents of Q fever, caused LIFE CYCLE SUMMARY by Coxiella bumeti, and boutonneuse fever (tick typhus), caused by Rickettsia conori, have The following information is adapted chieñy been isolated from A. variegatum. from Walker in Hoogstraal : Amblyomma variegatum is a 3-host tick. Ar gas persicus (Oken), the Fowl tick The female lays approximately 10,000-12,000 eggs DISTRIBUTION Preoviposition period 12 days Oviposition to hatching 53 days Argas persicus is primarily an Old World Larval prefeeding period 7 days species. Careful study ^^ of specimens from the Larva feeds 5 days New World believed to be A. persicus showed Premolting period 14 days that this tick plus three other closely related Nymphal pref eeding period 7 days but distinct, valid species are present. The other Nymph feeds 5 days species are A. radiatus reported from Florida, Premolting period 19 days Iowa, Texas, and Mexico; A. sanchezi reported Adult pref eeding period 7 days from Arizona, California, Nevada, New Mexico, Female feeds 12 days Texas, Utah, and Mexico; and A. miniatus Total 141 dayö reported from Panama, Trinidad, Colombia, Brazil, and possibly the United States (Geor- In areas with one rainy season each year, gia). Apparently A. persicus is rather rare in only one life cycle is completed per year; in the New World with very limited collections areas with two rainy periods, two generations reported from Maryland, Pennsylvania, Geor- may be expected each year. gia, California, and Paraguay. In this manual the name Argas persicus ECONOMIC IMPORTANCE group is used collectively when referring to the Amblyomma variegatum is a common vector above-named species, although it is recognized of Cowdria ruminantium which produces heart- that A. persicus is probably not the common water in cattle, sheep, and goats. This species species encountered in the United States. There is also a vector of Nairobi sheep disease. is confusion regarding the validity of older Apparently A, variegatum plays a role in the published material on the distribution, hosts, natural spread of dermatophilosis (bovine identification, and biology of the Argas ticks. streptothricosis), which is generally accepted Quite likely many of the older published ref- to be produced by Dermatophilus congolensis, erences to A. persicus in the Southwestern Epidemiological evidence indicates that there is United States were misidentifications of A. a relationship between the tropical bont tick radiatus and A. sanchezi. All conditions being and the development of the disease. In the equal, the biology of these species is probably laboratory, dermatophilosis has been trans- very similar. mitted from cattle to rabbits by adults of A. variegatum. '« See Kohls, Hoogstraal, Clifford and Kaiser (1970).

40 HOSTS Nymphs survive, .up to 509 days for 2nd stage Unfed Adults survive, .up to 2 years and 5 mos. In the New World the true A. persicus and (Some authors report longer periods.) A. miniatus have been collected only from chickens or chicken houses. Argas radiatus, and A. sanchezi parasitize poultry and various wild ECONOMIC IMPORTANCE avian hosts. These ticks may inflict extensive skin damage LOCATION ON HOST and produce large blood clots on their natural hosts during feeding. Light infestations cause The fowl tick attaches beneath the wings and emaciation, weakness, slow growth, and lowered other places where feathers are sparse. egg production. Heavy infestations cause ex- sanguination and death of the host. Turkeys and SEASONAL ACTIVITY newly hatched poults and chicks show the greatest mortality. Birds are attacked more The fowl tick occurs in greatest abundance freqeuntly during the warmer, drier seasons on birds during the warmer, drier seasons of of the year. the year. Argas persicus is the chief vector of Borrelia anserina, causative agent of a highly LIFE CYCLE SUMMARY fatal spirochetosis in chickens, turkeys, pheas- The following information is chiefly adapted ants, doves, and pigeons. It also transmits from Hooker, Bishopp, and Wood : Aegyptianella pullorum which produces fowl Argas persicus is a multihost tick. piroplasmosis in chickens and geese. Gothe reported tick paralysis in chickens The female may lay as many as 874 eggs infested with the South African strain of A. during her entire life. These are produced in as persicus. many as seven batches with a blood meal pro- The authors observed tick paralysis in a ceeding each batch of eggs. The maximum southern Maryland flock of chickens infested number of eggs in the first batch is 195 with a with A, persicus; 85 percent of the birds died peak of 245 eggs with the third batch. Only 47 within 1 month of being placed in the infested eggs were reported from the seventh oviposition. chicken house. Preoviposition period. .2 days to several months While A. persicus is not known to transmit Oviposition period in summer usually any human diseases naturally, its bite has been 4 to 10 days; reported to cause severe pain. The true A, Incubation of the eggs. . in summer, usually persicus rarely attacks man and other mammals. 8-11 days; in winter, up to 107 days Larvae engorge 2-10 days Boophilus annulatus (Say), Larvae molt 4-17 days the Cattle Fever tick Nymphs (1st, 2nd, and 3rd stage) engorge approx. 30 min.-2 hours 1st stage nymphs molt 7 to 28 days DISTRIBUTION 2nd stage nymphs molt. . in summer, At the beginning of the 1900's the cattle-fever 11-24 days; in winter, tick was widely distributed throughout the up to 195 days Southern United States. The species is now 3rd stage nymphs molt 9-12 days eradicated from the United States except for Females may engorge as many as periodic introductions on illegal movements or 7 times and feed each stray cattle from Mexico where Boophilus time for approx 30 min.-2 hrs... annulatus is still prevalent. This species is also Unfed larvae survive in cool weather, found in western and central Africa, and the up to 164 days; Sudan. If B. calcaratus is synonomous with B, in mid summer, annulatus, the range is extended to the Mediter- about 60 days ranean basin and the Near East.

II HOSTS infested area, as many as three or four genera- tions of B. annulatus are possible each year. Cattle are preferred hosts ; horses are next in Fewer generations are capable of being pro- preference; and sheep and goats are rarely duced each year in the northern part of the old attacked. Under certain conditions deer may cattle-fever tick zone because of the lower serve as suitable hosts. Attachment to man and temperature. dog has been reported, but neither is considered to be a satisfactory host for the development of B. annulatus. ECONOMIC IMPORTANCE LOCATION ON HOST This tick was once the most important external parasite of cattle in the Southern The cattle fever tick prefers to attach on the States. It caused serious economic loss by trans- dewlap, brisket, neck, axillae, abdomen, groins, mitting Babesia bigemina, causal protozoan of escutcheon, and the genitalia. Larvae and cattle fever (bovine piroplasmosis). The fever nymphs may be found in the ears. In severe not only caused death in cattle but secondary infestations ticks may be found any place on losses also included: (1) weakened condition the body. and stunted growth, (2) death due to gross SEASONAL ACTIVITY tick infestation, (3) losses of potential markets by both northern and southern cattle breeders, In the lower portion of the Southern States, (4) restriction on movement of southern cattle, prior to eradication, all parasitic stages were (5) lowered milk production, (6) damage to found on livestock throughout the year. How- hides and skins, (7) cost of maintaining ever, in both the upper and lower Southern quarantine line and facilities, (8) expenses in- States B, annulatus was most abundant on live- curred in attempt to reduce or eliminate ticks, stock during the spring, summer, and early fall. and (9) infested animals predisposed to attacks LIFE CYCLE SUMMARY by screwworms in Texas. In 1907, the primary and secondary losses due to Boophilus ticks in The information given below is adapted from the United States were estimated to be $100 the following sources: Hunter and Hooker; million each year. Hooker, Bishopp, and Wood; Bishopp; and The cattle fever tick has been incriminated in Graybill. the transmission of bovine anaplasmosis. Ex- Boophilus annulatus is a 1-host tick. perimentally, this species has transmitted, via The female lays as many as 4,500 eggs its eggy the spirochete, Borrelia theileri, causa- Preoviposition period 2-66 days tive agent of spirochetosis in cattle, sheep, Oviposition period 6-70 days goats, and horses. Also, experimentally, this Incubation of the eggs 19-202 days species has transmitted Theileria mutans, Larvae engorge and molt 5-16 days which causes benign bovine theileriosis. Nymphs engorge and molt 5-18 days Females engorge 4-14 days Boophilus decoloratus (Koch), Unfed larvae survive. up to 246 days the Blue tick The minimum parasitic period (from the at- tachment of larvae to dropping of engorged DISTRIBUTION females) is 20 days; the maximum parasitic period is 59 days; and the average is 32 days. The blue tick is widely distributed in western, The nonparasitic period (from the dropping central, eastern, and southern Africa. of the engorged female to death of the last larva) may be as short as 28 days in the HOSTS summer or extend up to 288 days, particularly if the engorged female drops in late summer^or Cattle are the chief hosts; horses are the early fall. second preference, with sheep and goats less Under very favorable conditions, particularly frequently parasitized. Antelopes are the most in the southern part of the old cattle fever tick important wild hosts.

42 LOCATION OF HOST time it was also established in southern Florida and in several counties in extreme southern The blue tick is commonly found on the dewlap, brisket, neck, axillae, udder, groins, Texas. scrotum, and escutcheon. Larvae and nymphs HOSTS are often found on the distal half of the ear flap. In heavy infestations ticks may be Apparently B. microplus has a slightly wider scattered over most of the body. host preference than B. annnlatus. The primary hosts for B, microplus are cattle, with horses SEASONAL ACTIVITY as the second preference. It is found more commonly on goats, sheep, and deer than is The blue tick is usually found on hosts B, annulatus. throughout the year, with the greatest abun- dance and activity occurring during the warmer LOCATION ON HOST months. On the primary host, this tick is commonly found on the dewlap, brisket, neck, axillae, LIFE CYCLE SUMMARY groins, abdomen, escutcheon, and the genitalia. The following information is adapted from Larvae and nymphs sometimes may be found Lounsbury in Theiler and du Toit and Theiler. in the ears. BoopMlus decoloratus is a 1-host tick. SEASONAL ACTIVITY The female lays up to 2,500 eggs Preoviposition period 6-9 days Larvae, nymphs, and adults may be found on Oviposition and incubation period... 3-6 weeks the host through the year in tropical and sub- Larvae engorge and molt 7 days tropical areas. Nymphs engorge and molt 7 days Females engorge 7-9 days LIFE CYCLE SUMMARY The following information is adapted from In South Africa, the engorged female usually several sources including Täte ; Hooker, Bishop, drops from the host 21-23 days after attaching and Wood ; Hitchcock ; and Legg : as the larva. Boophilus microplu^ is a 1-host tick. The female lays as many as 4,400 eggs ECONOMIC IMPORTANCE Preoviposition period 2-39 days The blue tick is one of the most common ticks Oviposition period 4-44 days attacking cattle in parts of Africa. It is an Incubation of the eggs 14-146 days important transmitter of the following diseases : Larvae engorge and molt 7-12 days bovine piroplasmosis (Babesia bigemina and B. Nymphs engorge and molt .5-17 days bovis), anaplasmosis (Anaplasma marginale Females engorge 5-23 days and A. centrale), and spirochetosis (Borrelia Unfed larvae survive up to 240 days theileri) of cattle, sheep, and goats. In addition to transmitting the above diseases, cattle are In Puerto Rico, the minimum parasitic period often heavily infested with blue ticks resulting (from the attachment of larvae to dropping of in severe anemia, weakness, and death due to engorged females) is 18 days; the maximum blood loss. parasitic period is 37 days; but the greater number of females engorge and drop by the 25th day. The length of the life cycle may range Boophilus micro plus (Canestrîni), from 41 to 300 days. Under favorable tropical The Tropical Cattle tick conditions, B. microplus may produce more than four generations each year. DISTRIBUTION Boophilus microphis is found in the hotter, ECONOMIC IMPORTANCE more humid parts of the West Indies, Mexico, Boophilus microplus is a reported vector of Central America, South America, Africa. the following agents : Babesia bigemina and B. Australia, the Orient, and Micronesia. At one argentina, which cause piroplasmosis in cattle.

13 Anaplasma marginale, which produces bovine ECONOMIC IMPORTANCE anaplasmosis ; and Theileria mutans, causative Heavy infestations of the winter tick inflict agent of benign bovine theileriosis. severe losses among deer, elk, and moose. Animals become weakened and often die as a Dermacentor albipictus (Packard), result of the parasitism. Cattle, and especially the Winter tick horses, may also be seriously affected by attacks of this tick. DISTRIBUTION Under experimental conditions D. albipictus is a vector of Anaplasma marginale, which This tick is widely but unevenly distributed produces bovine anaplasmosis. in the northern tier of States from Maine to Oregon and throughout the Western States Dermacentor andersoni Stiles south into Texas and Mexico. It is also widely Synonym^ Dermacentor ventustus Banks, distributed in Canada. the Rocky Mountain wood tick HOSTS DISTRIBUTION The common hosts for D. albipictus include horses, cattle, deer, elk, and moose. This tick is found from the western counties of Nebraska and the Black Hills of South LOCATION ON HOST Dakota to the Cascade and Sierra Nevada Mountains, and from northern Arizona and This tick prefers to attach on the dewlap, northern New Mexico to British Columbia, brisket, abdomen, groins, and axillae but may Alberta, and Saskatchewan, Canada. be found attached all over the body in heavy infestations. HOSTS SEASONAL ACTIVITY Important hosts for the adult stage include As the name indicates, D, albipictus is a cattle, horses, deer, dogs, man, elk, and several winter tick ; it occurs on livestock from autumn other large mammals. The immature stages until early spring. prefer many small mammals such as chipmunks, ground squirrels, meadow mice, woodchucks, and rabbits. LIFE CYCLE SUMMARY The following information is adapted from Bishopp and Wood: LOCATION ON HOST Dermacentor albipictus is a 1-host tick. The adults prefer to attach on the head, The female lays as many as 4,400 eggs neck, shoulders, dewlap, brisket, groins, and Preoviposition period 7-134 days escutcheon. Immature stages usually attach Oviposition period 19-42 days around the head, neck, and shoulders of small Incubation of the eggs 33-71 days mammals. Larvae engorge and molt 9-20 days Nymphs engorge and molt, .usually 9-12 days Females engorge 8-30 days SEASONAL ACTIVITY Unfed larvae survive up to 346 days Adults usually begin showing up on hosts in February or March, reach a maximum abun- On livestock, the parasitic period ranges from dance during April and May, and decline in approximately 28 to 60 days. The nonparasitic numbers by July. Immatures occur somewhat period (from the dropping off of the engorged later than do the adults; nymphs appear on female to death of last larva) ranges from 159 hosts early in April; larvae appear on hosts to at least 479 days. Under natural conditions early in June; and both disappear from hosts the winter tick produces one generation a year. by late summer.

44 LIFE CYCLE SUMMARY Dermacentor nitens Neumann Synonym, Anocentor nitens (Neumann), The following information is adapted from Hunter and Bishopp ; and Hooker, Bishopp, and the Tropical Horse tick Wood: DISTRIBUTION Dermacentor andersoni is a S-host tick. In the United States, the tropical horse tick is established only in southern Florida and The female lays as many as 7,400 eggs several counties in the extreme tip of southern Preoviposition period 6-41 days Texas. This tick is also common in Mexico, Oviposition period 15-32 days Central America, the West Indies, and northern South America. Incubation of the eggs 15-51 days Larvae engorge 2-8 days HOSTS Larvae molt 6-21 days The horse and other domesticated equines are Nymphs engorge 3-9 days the preferred hosts, but it also occurs on cattle, Nymphs molt usually 11-19 days deer, sheep, and goats. Females engorge 8-17 days Unfed larvae survive up to 117 days LOCATION ON HOST Unfed nymphs survive over 300 days The ears are the preferred site of attachment Unfed adults survive up to about 600 days for the tropical horse tick. This tick is unusual because the larvae, nymphs, and adults all occur in the ears. Ticks also attach in the nasal The normal life cycle requires 1 or 2 years diverticula, perianal area, groins, mane, and on for completion, with the 1-year cycle being the abdomen. In heavy infestations, ticks may common where small mammals are abundant. be found all over the body. A 3-year cycle may exist at high altitude and at the northern limits of the tick's range. SEASONAL ACTIVITY All parasitic stages may be found on the host throughout the year in enzootic areas. ECONOMIC IMPORTANCE LIFE CYCLE SUMMARY In the Northwestern United States, D, The following information is adapted from andersoni is very important as a parasite of man and livestock. It is the primary vector of Hooker, Bishopp, and Wood ; and Täte : Rickettsia rickettsi, disease agent of Rocky Dermacentor nitens is a 1-host tick. Mountain spotted fever, and it is also the chief The female lays as many as 3,400 eggs producer of tick paralysis in man and animals. Preoviposition period 3-15 days Other diseases transmitted or carried by this Oviposition period 15-37 days tick include Colorado tick fever of man, Incubation of the eggs 21-28 days tularemia, and Q fever. Larvae engorge and molt 8-16 days Nymphs engorge and molt, .approx. 7-14 days Bovine anaplasmosis is an important live- Females engorge 9-23 days stock disease suspected of being transmitted by Unfed larvae survive up to 71 days D. andersoni in the Northwestern States. The minimum parasitic period reported is 26 Causative agents of other diseases such as days ; the maximum parasitic period is 41 days ; canine piroplasmosis and arthropod-borne en- but the majority of the females probably cephalitis (Western type) have been experi- engorge and drop well before the maximum mentally transmitted by D. andersoni, but there period is reached. Under favorable tropical con- is no evidence to indicate that disease transmis- ditions several generations are completed each sion is a problem under natural conditions. year. 15 ECONOMIC IMPORTANCE LIFE CYCLE SUMMARY Dermacentor nitens is a vector of Babesia The following information is adapted from caballi, one of the organisms which causes Hooker, Bishopp, and Wood : equine piroplasmosis. Dermacentor occidentalis is a 3-host tick. The female lays up to 4,500 eggs This tick is a serious pest of horses in tropical Preoviposition period 4-17 days and subtropical areas where it is established. Oviposition period approx. 14 days The ears may literally become filled with ticks, Incubation of the eggs 16-38 days molted skins, and excrement which develop a Larvae engorge 3-7 days very offensive odor. Infection and suppuration Larvae molt 6-12 days often follow and predispose the animal to Nymphs engorge 4-9 days attack by the screwworm, Cochliomyia homini- Nymphs molt 13-22 days vorax. Massive infestations of D. nitens can Females engorge 6-17 days cause anemia, loss of weight, and even death. Unfed larvae survive up to 124 days Unfed nymphs survive up to 108 days Dermacentor occidentalis Marx, Unfed adults survive up to 359 days the Pacific Coast tick ECONOMIC IMPORTANCE DISTRIBUTION This tick apparently plays a role in the As the common name implies, D. occidentalis maintenance and spread of bovine anaplasmosis. is confined to the Pacific Coast. It is established In California, it has also been found associated in and to the west of the Cascade Range and with cases of tick paralysis in livestock. Sierra Nevada Mountains in Oregon and Cali- Dermacentor occidentalis is capable of trans- fornia. It has also been found in northern Baja mitting the causative agents of tularemia and California, Mexico. Rocky Mountain spotted fever, and it has been found naturally infected with the virus of Colorado tick fever and the rickettsia of Q HOSTS fever. The common hosts for the adult stage include cattle, horses, deer, dog, sheep, and man. Im- Dermacentor variabilis (Say), mature ticks are found on a variety of smaller the American dog tick mammals such as chipmunks, ground squirrels, field mice, and wood rats. DISTRIBUTION LOCATION ON HOST This tick is widely distributed over the eastern half of the United States, and in parts The adult is the only stage commonly found of California, Idaho, Oregon, Washington, and on livestock and it may be found distributed Montana. It is also established in areas of over the host's body. Canada and Mexico.

SEASONAL ACTIVITY HOSTS The larvae and nymphs are most abundant The common hosts for the adult stage include on hosts in the spring and summer. Adults man, dogs, cattle, horses, deer, and many other have been taken from livestock throughout the wild and domesticated mammals. The immature year but seem to reach a peak of abundance in stages engorge mainly on small rodents, espe- April and May. cially meadow mice.

46 LOCATION ON HOST The American dog tick transmits the dis- Adults seem to prefer to attach on the neck, ease agent of tularemia and it is partially dewlap, brisket, axillae, groins, genitalia, abdo- responsible for the maintenance of infection in men, and escutcheon. In massive infestations rodents in nature. Stage-to-stage, but not trans- they may be found all over the body. Immature ovarial, transmission of bovine anaplasmosis stages feed mainly around the head, neck, and (Anaplasma marginale) has been demonstrated shoulders of small mammals. with this tick.

SEASONAL ACTIVITY Haemaphysalis leachi leachi ^^ In the Central and Northern States, adult (Audouin), the Yellow dog tick activity begins around mid-April, peaks in June, and thereafter declines until September. DISTRIBUTION In the Southern States, ticks in all stages may The yellow dog tick is distributed throughout be found on hosts throughout the year, although the Ethiopian zoo-geographical realm, except in they are usually more abundant in the spring. desert areas receiving less than 20 inches rainfall annually. LIFE CYCLE SUMMARY The following information is adapted from HOSTS Smith, Cole, and Gouck; and Bishopp and Smith : The dog is the primary host for the adults of H, L leachi, but they may also be found on cats Dermacentor variabilis is a 3~host tick. and the larger wild carnivores. Immatures The female lays approximately 6,500 eggs usually parasitize field rodents but may feed on Preoviposition period 3-58 days domestic dogs. Oviposition period 14-82 days Incubation of the eggs 2&-57 days LOCATION ON HOST Larvae engorge 3-13 days The neck and shoulders are the preferred Larvae molt 6-247 days attachment sites. Nymphs engorge 3-11 days Nymphs molt 24-291 days SEASONAL ACTIVITY Females engorge 5-27 days Unfed larvae survive up to 540 days Haemaphysalis L leachi is most abundant on Unfed nymphs survive up to 584 days hosts during the warmer seasons of the year. Unfed adults survive up to 1,053 days LIFE CYCLE SUMMARY In the Southern States, the life cycle may possibly be completed in 1 year, but in the The following information is adapted from Northern States the 2-year cycle may be more Theiler; and Nuttall: common. Haemaphysalis L leachi is a 3-host tick. The female lays up to 4,800 eggs ECONOMIC IMPORTANCE Preoviposition period 3-7 days Dermacento?' variabilis is the principal vector Incubation of the eggs 26-37 days of Rickettsia rickettsi, the causative organism of Rocky Mountain spotted fever of man, from ^^ The subspecies Haemaphysalis leachi muhsami San- the Mississippi Valley east to the Atlantic tos Dias is also widely distributed in Africa. It is Ocean and south to the Gulf of Mexico, includ- smaller in size and prefers to feed on small carnivores, such as mongooses, and wildcats, instead of on wild or ing Texas and Oklahoma. This tick also pro- domestic canines. Disease relationship of H, L muh- duces tick paralysis in man and dogs. sami are unstudied.

47 Larvae engorge 2-7 days SEASONAL ACTIVITY Larvae molt about 30 days In the Southern States, H. leporispalustris Nymphs engorge 2-7 days may be found on hosts throughout the year, but Nymphs molt 10-16 days is more abundant on hosts in spring and fall. Females engorge 4-16 days In the Northern States, this tick is usually not Egg to egg 81-120 days found on hosts during the winter, and is most Unfedlarvaemay survive. .6 months or longer abundant during the spring and summer and Unfed nymphs may survive.. 2 months or longer declines in the fall. Unfed adults may survive.. 7 months or longer In nature, the yellow dog tick apparently LIFE CYCLE SUMMARY produces two generations each year. The following information is adapted from Hooker, Bishopp, and Wood; and Rohr and ECONOMIC IMPORTANCE Hadwen in Nuttall and Warburton : The yellow dog tick transovarially transmits Haemaphysalis leporispalustris is a 3-host Babesia canis (canine piroplasmosis). Like tick. many other ticks, it has been found naturally The female lays. up to 2,400 eggs infected with Coxiella burneti, which causes Preoviposition period .2-18 days Q fever. Oviposition period 3-57 days In South Africa, urban cases of boutonneuse Incubation period 22-61 days fever are associated with dogs infested with Larvae engorge. 4-11 days adults of H, I, leachi. Human infection is often Larvae molt 18-134 days acquired by contamination of the skin and eyes Nymphs engorge 4-11 days with Rickettsia conori from yellow dog ticks Nymphs molt 14-124 days which are crushed as they are picked off dogs. Females engorge 19-25 days Unfed larvae survive up to 258 days Haemaphysalis leporispalustris Unfed nymphs survive up to 342 days (Packard), the Rabbit tick Unfed adults survive up to 588 days

DISTRIBUTION In the Southern States, under favorable con- ditions, as many as two complete life cycles This tick is widely distributed in North may be completed each year. America, from Alaska and Canada southward into Mexico. It has also been reported from ECONOMIC IMPORTANCE parts of Central and South America. The rabbit tick rarely attacks livestock and HOSTS man. It is a common parasite of rabbits and birds and massive infestations often weaken Rabbits are the preferred hosts for the adult and kill them. stage of this tick. Birds of many kinds, espe- This tick plays an especially important role cially ground-inhabiting birds, and small mam- in the maintenance and spread of Rocky Moun- mals serve as hosts for the immature stages. tain spotted fever and tularemia among wild Veterinary Services personnel have also taken animals. Haemaphysalis leporispalustris is a several collections of nymphs from cattle and carrier of Coxiella burneti, causative agent of deer. Q fever.

LOCATION ON HOST Hyalomma marginatum Koch, On rabbits, the ticks usually attach to the the Mediterranean Hyalomma ears, around the eyes, and on other parts of the head. The favorite attachment sites on birds are DISTRIBUTION the top and back of the head and around the The ticks generally accepted as being eyes and ears. Hyalomma marginatum represent a complex of

48 several subspecies ^^ that are found in southern Apparently one generation is normally pro- Europe, southern Russia, north Africa, the duced each year. Middle East, and in scattered areas of other parts of Africa and Asia. ECONOMIC IMPORTANCE HOSTS As a group, the genus Hyalomma is of con- siderable veterinary and medical importance as Common hosts for the adults are cattle, vectors and reservoirs of disease-producing horses, sheep, goats, and camels. Nymphs also agents. The ticks of the Hyalomma marginatum. feed on domestic animals but are more common group are reportedly vectors of the disease- on small wild mammals and birds. Larvae feed producing agents of bovine theileriosis (Thei- only on small animals. leria spp.), equine piroplasmosis (Bab esta caballi and B. equi), and canine piroplasmosis LOCATION ON HOST (B, canis). In man, some of these ticks are These ticks are commonly found in the peri- vectors of the virus of Crimean hemorrhagic anal area, groins, on the genitalia and udder, fever, Q fever (Coxiella burneti), and bouton- axillae, and on the brisket and dewlap. neuse fever (Rickettsia conori) and are also incriminated in the maintenance and spread of SEASONAL ACTIVITY brucellosis (Brucella melitensis). The adults are found on hosts most frequently Hyalomma ticks, other than the H. marginatum in the spring and summer; the larvae and group, are also involved in the transmission of nymphs are usually found on hosts in the other disease-producing agents. For example, summer. some strains of H. truncatum are known to be involved in the production of sweating sickness LIFE CYCLE SUMMARY in cattle, sheep, and goats in parts of southern Africa. Other species of Hyalomma are re- The following information is adapted from portedly able to transmit the causative agents Nuttall (1913).13 of bovine anaplasmosis (Anaplasma marginale) Hyalomma marginatum may act as a 2-host and bovine ehrlichiosis (Ehrlichia bovis). or 3-host tick. Female lays up to 15,500 eggs Ixodes ricinus (Linnaeus), Preoviposition period 6-12 days the European Castor Bean tick Oviposition to hatching 35 days Larval prefeeding period 7 days DISTRIBUTION Larvae feed 6 days This tick is common throughout most of Larvae molt 16 days Europe, including the British Isles, and is Nymphal pref eeding period 7 days found in north Africa (Tunisia and Algeria) Nymphs feed 6 days and limited areas of Asia. Contrary to earlier Nymphs molt 20 days reports, this tick has never been established in Adult pref eeding period. 7 days North America. Female feeds 6 days Total ., 116 days HOSTS Unfed larvae survive up to 345 days Unfed nymphs survive up to 89 days Common hosts for the adults include sheep, Unfed adults survive over 421 days cattle, dogs, horses, and deer ; immatures have been reported from various birds and even lizards. ^* Hoogstraal and Kaiser recognize several subspecies of H. marginatum, namely H. marginatum marginatum, H, marginatum rufipes, H. m,arginatum isaaci^ and H. LOCATION ON HOST marginatum turanicum. This tick prefers to attach on areas where '^ Hoogstraal reports that the life cycle studies of H. aegyptium conducted by Nuttall were undertaken with the hair is short or the skin is bare, such as the specimens now recognized as H. marginatum. face, ears, axillae, groins, and escutcheon. 19 SEASONAL ACTIVITY In European Russia and parts of northern and central Europe, /. ricinus is the vector of In northern areas this species is found on the virus which causes tickborne encephalitis hosts in the summer. In milder temperate in man. regions of Eurasia it may have two activity periods, spring and autumn. In Algeria and Tunisia it is a winter tick. Ixodes scapularis (Say), Black-legged tick LIFE CYCLE SUMMARY DISTRIBUTION The following information is adapted from Nuttall (1911): This tick is common in the Southeastern Ixodes ricinus is a 3-host tick. States, Texas, eastern Oklahoma, and along the The female lays up to 3,000 eggs Atlantic coast to Massachusetts. Recently it Preoviposition period 8-27 days was found in Wisconsin and Minnesota. It also Oviposition and incubation of extends into Mexico. the eggs 42-252 days Larval prefeeding period 10-570 days HOSTS Larvae engorge 3-6 days Larvae molt 28-140 days The adults prefer to feed on larger mammals Nymphal pref eeding period 10-540 days such as cattle, horses, deer, dogs, sheep, hogs, Nymphs engorge 3-5 days and man. Larvae and nymphs feed primarily on Nymphs molt 56-360 days birds, small mammals, and occasionally lizards. Adult pref eeding period 10-810 days LOCATION ON HOST Females engorge 8-14 days Total 178-2,724 days The adults usually attach on the head and Unfed larvae survive up to 19 months neck of dogs and other larger mammals. Unfed nymphs survive up to 18 months Unfed adults survive up to 27 months SEASONAL ACTIVITY As long as 3 years is normally required to The adults are more abundant on hosts from complete the life cycle ; the larvae feed the first late fall to spring; immature stages are more year, the nymphs the second year, and the abundant on hosts in the spring and summer. adults the third year. Under very favorable conditions the life cycle may be completed in LIFE CYCLE SUMMARY less than 3 years. The following information is adapted from Hooker, Bishopp, and Wood ; and Harris : ECONOMIC IMPORTANCE Ixodes scapularis is a 3-host tick. In Europe, this species is responsible for The female lays approximately 3,000 eggs transmitting bovine piroplasmosis (Babesta Preoviposition period 10-19 days bovis), anaplasmosis (Anaplasma marginale), Incubation of the eggs 48-135 days the virus of louping ill, and tick-borne fever Larvae engorge 3-9 days (Ehrlichia phagocytophila) of cattle, sheep, and Larvae molt 22-49 days goats. It has been found naturally infected with Nymphs engorge 3-8 days the causative agent (Coxiella burneti) of Q Nymphs molt 25-56 days fever. Females engorge 8-9 days In Great Britain, /. ricinus is associated with Unfed larvae survive more than 75 days the production of tick pyemia (Staphylococcus Unfed nymphs survive more than 60 days aureus) in young lambs. Although the ticks are Unfed adults survive undetermined not thought to transmit the bacteria, the wounds produced by its feeding permit the Under normal conditions, the black-legged organism to gain entrance readily into various, tick apparently completes one life cycle each parts of the body and produce abscesses. year. 50 ECONOMIC IMPORTANCE The female tick can lay over 2,000 eggs in her productive life of 3 or more years. At the present time, /. scapularis is not known to be involved in the natural transmis- Preoviposition period 15-55 days sion of disease agents of livestock and man.^* Incubation of the eggs 23-40 days Experimentally, stage-to-stage transmission of Larval prefeeding period 3-7 days Anaplasma marginale has been reported. Ticks Larval feeding 7-10 days have been found naturally infected with Larval molt 10-28 days Francisella tularensis and experimental trans- First nymphal stage does not feed mission of tularemia has been reported. First nymphal molt 8-39 days Second nymphal molt ^^ 14-30 days Ornithodoros coriaceus Koch, Third nymphal molt 10-60 days Fourth nymphal molt 16-74 days the Pajaroello tick Fifth nymphal molt 28-92 days Sixth nymphal molt 35-114 days DISTRIBUTION Seventh nymphal molt 33-53 days This tick occurs along the Pacific Coast of Adult feeding i« 15-30 minutes California from Humboldt County in the north Total days for complete cycle 202-602 to San Diego County in the south. It is also Unfed adults survive for about 9 months believed to occur along the coast of Mexico as Fed males survive about. .3 years and 7 months far south as the State of Chiapas. Fed females survive for more than 5 years The length of the cycle is influenced by the HOSTS temperature and availability of hosts. Under Common hosts are cattle and deer. It also natural conditions there is probably one genera- feeds on man and probably on a variety of tion each year, but in many instances, a genera- other mammals. tion may take 2 years to develop.

LOCATION ON HOST ECONOMIC IMPORTANCE The nymphs and adults remain in protected The pajaroello tick readily attacks man and areas under trees in old deer- and cattle-bedding livestock and its venomous *'bite" is reported to grounds and attack livestock, wildlife, and man be very painful. when they pause in these locations. The ticks Although this species is not known to trans- probably feed most readily on an accessible mit any disease, it should not be ruled out as a area, most likely the legs and ventral portions potential vector until adequate research has of the body. been conducted.

SEASONAL ACTIVITY Otobius megnini (Dugès), In some areas this tick is active throughout the Spînose ear tick the year, but in other locations it is active only in the warmer months. DISTRIBUTION The spinose ear tick is a native of the LIFE CYCLE SUMMARY Americas and is very abundant in the South- The following information is adapted from western and Western United States and Mexico. Loomis; Herms; and Smith. It has been carried to other areas of the world Ornithodoros coriaceus is a multihost tick. ^^ Each nymphal stage, except for the first, generally " Recent reports incriminate /. scapularis as a pos- feeds for 15-30 minutes. sible vector of piroplasmosis (Babesia microti) in ^®The adults normally feed several times over an humans on Nantucket Island, Massachusetts. Babesia extended period and the female usually lays a batch of microti is a parasite of field mice and deer mice. eggs after each feeding. 51 in the ears of the hosts. Otobius megnini is now completion of several life cycles is possible each established in parts of Africa, Madagascar, year. India, and Hawaii, as well as in Canada (British Columbia) and South America. ECONOMIC IMPORTANCE In arid and semiarid areas of the South- HOSTS western and Western States this species is a The larvae and nymphs are found in the ears serious pest of cattle and horses. By attaching of many large mammals, particularly cattle, deep in the ears, it causes considerable irrita- horses, sheep, deer, goats, and dogs. There are tion and pain. Animals become restless, shake a few reports of human infestations. and rub their heads, and run about until they become exhausted. Dairy animals produce less milk and beef cattle often show significant loss LOCATION ON HOST of weight. The larvae and nymphs are found deep in the The injury produced by the spinose ear tick ears of the host. Adults do not have functional predisposes the host to attack by screwworms mouthparts, do not feed, and are not found on (Cochliomyia hominivorax) and secondary bac- animals. Careful inspection of the ears is terial invaders of the inner ear; death often essential to locate this species. The use of a follows. curette is needed to establish definitely that Otobius megnini has been found naturally in- ticks are not present. fected with Coxiella burneti and may be an important focus of infection for livestock. SEASONAL ACTIVITY Immature stages may be found on animals Rhipicephalus appendiculatus throughout the year, but the injurious effects Neumann, the Brown ear tick are usually most pronounced in the winter and spring. DISTRIBUTION The brown ear tick is widely distributed in LIFE CYCLE SUMMARY parts of southern, central, and eastern Africa. The following information is chieñy adapted It occurs in the wetter areas and is absent in from Hooker, Bishopp, and Wood : deserts and in areas without shrub cover. This is an aberrant 1-host tick. Only the larval and nymphal stages feed ; the adult stage HOSTS completes the life cycle on food obtained during This is primarily a cattle tick and all para- the second nymphal stage. The last molt, which sitic stages thrive on cattle. Secondary hosts produces the adults, occurs in the environment include sheep, goats, dogs, buffalo, antelopes, away from the host. and other mammals. The immatures are re- Female lays as many as 1,500 eggs ported from hares and other smaller mammals, Preoviposition period usually 8-12 days but prefer the same larger hosts as the adult Oviposition period, .approximately 14-180 days ticks. Incubation of the eggs 10-23 days Larvae engorge and molt 7-12 days Nymphs ^^ engorge and molt 31-209 days LOCATION ON HOST Adults do not feed The following statement is from Yeoman and Unfed larvae survive... approximately 80 days Walker : Unmated females survive up to 638 days "By far the most important predilection site Loomis reports that the life cycle may be for R. appendiculatus is the inside of the flap completed (in the laboratory) in 62-118 days. of the ear, in particular the proximal third of Therefore, under favorable conditions, the the upper edge, where the fringe of long hairs grows. Owing to the curvature of the ear, quite " The spinose ear tick has two nymphal stages. large numbers of ticks can be^ttached ^n Ihia 52 site without being visible to anyone merely bigemina by Boophilus microplus; instead, only looking at the standing animal. We have known trans-stadial (stage-to-stage) transmission field staff and cattle owners to deny the pres- occurs. For instance, infection is either picked ence of any ear ticks but when the animals up by the larva and transmitted to a susceptible were properly restrained and the ears were host by the nymph, or it is picked up by the opened ticks were found to be numerous." nymph and transmitted by the adult. Infection This direct quotation is used because it is not carried through the egg to the larva of clearly points out the necessity and importance the next generation. of carefully examining the ears of imported livestock and exotic animals. Other protozoal diseases of cattle transmitted In heavy infestations ticks may be found by R, appendiculatus include Corridor disease on the head, neck, abdomen, genitalia, and (T, lawrencei), benign bovine theileriosis (T. extremities. mntans), and bovine piroplasmosis (Babesia bigemina). SEASONAL ACTIVITY Three viral diseases of sheep are transmitted In South Africa, the adults are reported to by this tick: louping ill (experimentally), be most abundant on hosts from November to Nairobi sheep disease, and Kisenyi sheep March; the immatures are absent on hosts disease. during this period. The larvae are usually most In South Africa, R, appendiculatus has been abundant on hosts during May through July associated with the development of tick toxi- and decline in August. The nymphs occur on cosis in cattle following very heavy tick hosts from June through September and decline infestations. in October. The wounds produced by the feeding of the LIFE CYCLE SUMMARY brown ear tick can become infected and de- The following information is adapted from velop abscesses which often result in severe Theiler; and du Toit and Theiler: injury or even loss of the ears. RMpicephalus appendiculatits is a 3-host tick. The female lays up to 5,700 eggs Rhipicephalus evertsi evertsi Preoviposition 5-40 days Neumann, the Red—legged tick Oviposition to hatching 28 days-3 months Larva feeds 3-7 days DISTRIBUTION Premolting period 10-49 days Nymph feeds 3-7 days The red-legged tick is widely distributed in Premolting period 10-61 days parts of eastern, western, central, and southern Female feeds 4-10 days Africa as well as in the mountains of Yemen Unfed larvae survive up to 10 months in southwestern Arabia.^^ Uaafed nymphs-suxvive...... ^^^^ 15 months In September 1960, R, e, evertsi was found on Unfed adults survive up to 2 years a variety of wild animals confined in two zoological compounds in Florida and on a wild In areas where there is a single rainy season each year, the brown ear tick completes one game farm in New York. Following a concerted life cycle a year. However, in areas with two eradication effort, the red-legged tick was de- rainy seasons each year, as many as three clared eradicated from the United States in generations may occur within a 1-year period. January 1962. This tick is frequently found on zebras, antelopes, and other wild animals from ECONOMIC IMPORTANCE Africa which are being held in quarantine prior to release for entry into the United States. The brown ear tick is the most important tick involved in the transmission of East Coast fever (Theileria parva) of cattle in eastern, ^® In the very dry regions of southwest Africa, the subspecies Rhipicephalus evertsi mimeticus Donitz re- central, and southern Africa. Theileria parva is places R. e. evertsi. Both subspecies occur together in not transovarially transmitted as is Babesia the savannahs of western equatorial Africa.

53 HOSTS paralysis in sheep. Heavy infestations cause The adults commonly occur on domesticated "tick worry.*' equines, cattle, goats, and sheep and on wild antelopes, zebras, and several other large game Rhipicephalus pulchellus Gerstacker, animals. Immature stages usually feed on the the Zebra tick same hosts as the adult ticks, but have been known to occur on smaller mammals such as DISTRIBUTION hares, elephant shrews, tree rats, and grass This is an east African tick and is primarily mice. found from northern Tanganyika through eastern Kenya into Ethiopia, and Somalia. LOCATION ON HOST Rhipicephalus pulchellus is occasionally found Adults prefer to attach in the peri-anal area, on zebras and other African animals which are under the base of the tail, and less frequently being held in quarantine at the U.S. Depart- on the teats, groins, and scrotum. Immatures ment of Agriculture quarantine facility for the are found deep in the convolutions of the ex- Port of New York at Clifton, N.J. ternal ear. A curette should be used in examin- ing the ears for the immature stages. HOSTS This tick is especially fond of zebras, but SEASONAL ACTIVITY likes the rhinoceros and a variety of other large This tick can occur on hosts throughout the herbivores. It feeds on common domesticated year but is more active in the summer than in animals and readily attacks man. The larvae the winter. and nymphs apparently feed on the same hosts as the adults. LIFE CYCLE SUMMARY LOCATION ON HOST The following information is adapted from Theiler; and du Toit and Theiler: The zebra tick is usually found on the dew- Rhipicephalus e. evertsi is a 2-host tick. lap, brisket, abdomen, axillae, groins, peri-anal Female lays 5,000-7,000 eggs area, and in the tail switch. Preoviposition period 6-24 days Eggs hatch 4-10 weeks SEASONAL ACTIVITY Larvae and nymphs on host 10-15 days In enzootic areas this species may be found Nymphs molt 42-56 days on the host throughout the year. Females engorge 6-10 days Total 92-175 days LIFE CYCLE SUMMARY Unfed larvae survive up to 7 months The following information is adapted from Unfed adults survive up to 14 months Walker. Rhipicephalus pulchellus is a 3-host tick. ECONOMIC IMPORTANCE Preoviposition period 6 days Rhipicephalus e, evertsi is a very important Larvae hatch 39 days tick in the areas of eastern, western, central, Larvae harden i» and southern Africa where it is established. It Larvae engorge 3 days is known to transmit the following diseases: Larvae molt 11 days bovine piroplasmosis (Babesia bigemina), Nymphs harden i^ equine piroplasmosis (B, equi), East Coast Nymphs engorge 3 days fever (Theileri parva), benign bovine theileri- Nymphs molt 15 days osis (T, mutans), ovine theileriosis (T, ovis), Adult harden i» benign ovine ehrlichiosis (Ehrlichia ovina),^ Adults engorge 11 days and spirochetosis (Borrelia theileri) of cattle, ^* Accurate records of time required by each stage sheep, goats, and horses. The red-legged tick for hardening were not kept, by¿ this period is^ fre- has been incriminated in the production of tick quently accepted to be approximately 1 week. 54 ECONOMIC IMPORTANCE and between the toes. The immatures often attach in the long hair on the neck. In heavy The zebra tick is a vector of the virus of infestations, all active stages may be found Nairobi sheep disease. attached to the hairy parts of the body. Since Babesia equi is a very common parasite in the wild zebra of eastern Africa, this tick SEASONAL ACTIVITY should remain in a suspect category as a po- tential vector of this protozoal disease-producing This tick is found on hosts throughout the agent of equines. year in tropical or subtropical areas. In warm- temperate areas, where definite seasonal changes Rhipicephalus sanguineus occur, ticks are commonly found on hosts from early spring until fall. Few ticks are found on (Latreille), the Brown Dog tick animals during the winter. The brown dog tick is unable to survive outdoors in the Northern DISTRIBUTION States, but when provided protection in heated Rhipicephalus sanguineus is one of the most houses and kennels, it is commonly found as far widely distributed tick species in the world. It north as Connecticut. is believed to be a native of Africa, but has been distributed throughout the tropical and LIFE CYCLE SUMMARY warm-temperate parts of the world with the The following information is adapted from migration of man and his dogs. The brown dog Hooker, Bishopp, and Wood; and Nuttall in tick is established in North, Central, and South Hoogstraal. America, the West Indies, Africa, Madagascar, Rhipicehalus sanguineus is a 3-host tick. the Middle East, East Indies, China, Australia, The female lays approximately 4,000 eggs Micronesia, southern Europe, and other areas. Preoviposition period 3-83 days Incubation of the eggs 8-67 days HOSTS Larvae engorge .3-7 days In the United States, the brown dog tick Larvae molt 6-23 days almost exclusively attacks dogs; when it is Nymphs engorge .4-9 days found on other hosts such as horses, cattle or Nymphs molt 12-129 days man, there is usually a history of close associa- Females engorge 6-50 days tion with dogs. Unfed larvae survive up to 253 days In other areas of the world, R. sanguineus Unfed nymphs survive up to 183 days has been reported from a wide variety of Unfed adults survive up to 568 days medium- and larere-size mammals and ground- Under favorable conditions, the life cycle may feeding birds. Some of these hosts include be completed in 63 days ; in warm areas, several buffalo, camel, cat, cattle, deer, goat, horse, generations may be expected each year. sheep, lion, zebra, ground-feeding birds (ostrich, bustard, ibis, hornbill, buzzard), hare, hedge- ECONOMIC IMPORTANCE hog, reptiles, and man. This unusually wide host range leads one to suspect that R, sangui- The brown dog tick is an exceedingly trouble- neus has either developed physiological races some pest of dogs, causing discomfort, blood with adaptation to particular hosts, or it con- loss, and disease. In the United States, it is a sists of a complex of distinct species which are vector of Ehrlichia canis (—Rickettsia canis), morphologically, if not physiologically, similar which causes canine ehrlichiosis, and Babesia to the classical brown dog tick. In Africa, the canis, which causes canine piroplasmosis. immature stages of R. sanguineus occur on a The Rhipicephalus sanguineus complex is a wide range of small mammals. very eflicient vector of many disease-producing agents. In other areas of the world, it is in- criminated in the natural or experimental LOCATION ON HOST transmission of many diseases of man and On the dog, the adult stage is commonly animals, including boutonneuse fever (Rickettsia found in the ears, along the nape of the neck, conori), Rocky Mountain spotted fever (R.

55 rickettsi), spirochetosis (Borrelia theileri) dog tick should remain in a suspect category tularemia (Francisella tularensis), equine piro- until the questions regarding classification and plasmosis (Babesia caballi and B. equi), anaplas- disease transmission are resolved. mosis (Anaplasma marginale), Q fever (Coxi- In the United States, R. sanguineus often ella burneti), and other diseases. See Hoogstraal becomes an annoying pest in households where (1956) and Neitz. dogs are kept. All active stages may be found The disease relationships should not be as- crawling about the walls, curtains, and furni- sumed to apply to R. sanguineiis, which is now ture. The homeowner often becomes greatly established in the United States. The U.S. alarmed, but fortunately this tick does not "race" of the brown dog tick is not commonly readily feed on man and is not known to found on hosts, other than dogs, and it is not naturally transmit any disease of man in the known to be important in the transmission of United States. Elimination of brown dog ticks diseases other than canine ehrlichiosis and from premises is difficult because of the hardi- piroplasmosis. The United States form of R. ness and longevity of all active stages, the ready sanguineus may or may not be capable of availability of the canine host, and the develop- transmitting all the diseases attributed to it ment of acaricidal-resistant strains in some throughout the world. Nevertheless, the brown areas.

XV. CHECKLIST OF THE TICKS OF THE UNITED STATES

Scientific Name Principal Host(s)

Family Argasidae Genus Argas Latreille : brevipes Banks Owls, sparrow hawk, woodpecker cooleyi Kohls and Hoogstraal Cliff swallow giganteu^ Kohls and CliflFord Several wild birds miniatus Koch Chicken persicus (Oken) Chicken radiatus Railliet Chicken, wild turkey, vulture sanchezi Dugès Chicken, dove, quail, turkey

Genus Antricola Cooley and Kohls : coprophilus (Mclntosh) Bats

Genus Ornithodoros Koch : capensis Neumann Marine birds concanensis Cooley and Kohls Probably bats cooleyi Mclvor Small mammals coriaceus Koch Deer, cattle, man denmarki Kohls, Sonenshine and Clifford Marine birds dyeri Cooley and Kohls Bats eremicus Cooley and Kohls Mice hermsi Wheeler, Herms, and Meyer Chipmunks, deer mice, wood rats

Ornithodoros kelleyi Cooley and Kohls : Bats parkeri Cooley Various small mammals, burrowing owl sparnus Kohls and Clifford Wood rats stageri Cooley and Kohls Bats 56 XV. CHECKLIST OF THE TICKS OF THE UNITED STATES—Con.

Scientific Name—Con. Principal Hosts (s)—Con.

Family Argasidae—Con.

talaje (Guérin-Méneville) Wild rodents turicata (Dugès) Various rodents, pigs, burrowing owls yumatensis Cooley and Kohls Bats

Genus Otohius Banks : lagophilus Cooley and Kohls Rabbits megnini (Dugès) Livestock

Famihj Ixodidae

Genus Amblyomma Koch : americanum (Linnaeus) Livestock, deer, birds, man cajennense (Fabricius) Livestock, man dissimile Koch Snakes, Iguana imitator Kohls Variety of domestic and wild animals inornatum (Banks) Small mammals, cattle, deer maculatum Koch Variety of mammals and birds tuberculatum Marx Gopher-tortoise

Genus Aponomma Neumann elaphensis Price Snake

Genus Boophilus Curtice annulatus^^ (Say) Cattle micropluis^^ (Canestrini) Cattle

Genus Dermacentor albipictus (Packard) Cattle, horses, deer andersoni Stiles, syn. D. venustus Banks Variety of mammals halli Mclntosh Peccary (Javelina) hunteri Bishopp Bighorn sheep nigrolineatus (Packard) Cattle, horses, deer

mten^ Neumann, syn. Anocentor nitens (Neumann) Horses occidentalis Marx Variety of mammals parumapertus Neumann Rabbits variabilis (Say) Variety of mammals

' Not presently established ; occasionally introduced into Texas from Mexico.

;>v XV. CHECKLIST OF THE TICKS OF THE UNITED STATES—Con.

Scientific Name—Con. Principal Hosts (s)—Con.

Family Ixodidae—Con.

Genus Haemaphysalis Koch chordeilis (Packard) Birds leporispalustris (Packard) Rabbits

Genus Ixodes Latreille aßnis Neumann Deer, small mammals angusties Neumann : Variety of small mammals auritulus Neumann Birds baergi Cooley and Kohls Cliff swallows banksi Bishopp Small mammals brunneits Koch Birds calif ornicus Banks Birds conepati Cooley and Kohls Hog-nosed skunk cookei Packard Small mammals dentatus Marx Cottontail rabbit diversifossus Neumann Raccoon eadsi Kohls and Clifford Small rodents hearlei Gregson Red squirrel holdenreidi Cooley Pocket gopher howelli Cooley and Kohls Birds jellisoni Cooley and Kohls Mice kingi Bishopp Small mammals marmotae Cooley and Kohls Woodchucks marxi Banks Squirrels minor Neumann Birds muris Bishopp and Smith Small rodents neotomae Cooley Small mammals ochotonae Gregson Pika pacificiis Cooley and Kohls Variety of mammals peromysci Augustson Mice rugosus Bishopp Skunk, dog scapularis Say Variety of mammals and birds sculptus Neumann Ground squirrels signatns Birula Sea birds soricis Gregson Shrews spinipalpis Hadwen and Nuttall Small mammals texanus Banks Small mammals tovari Cooley Hares uriae White Marine birds woodi Bishopp Wood rat

Rhipicephalus Koch : sanguineus (Latreille) Dogs

3« XVI. REFERENCES

ALLRED, D. M. and ROÖCOE, E. J. BEQUAERT, J. C. 1956. LIFE HISTORY OF THE TICK DERMA- 1945. THE TICKS, OR IXODOIDEA, OF THE CENTOR PARUMAPERTUS IN UTAH. Jour. NORTHEASTERN UNITED STATES AND EAST Parasitol. 42: 516-522. ERN CANADA. Ent. Americana 25 (2): 73-120; Ent. Americana 25 (3) : 121-184; and Ent. Americana ANASTOS, G. 25 (4) : 185-224. 1950. THE SCUTATE TICKS, OR IXODIDAE, OF INDONESIA. Ent. Americana 30 (1-4) : 1-144. BISHOPP, F. C. 1913. THE OCCURRENCE OF THE AUSTRALIAN ARTHUR, D. R. CATTLE TICK AND THE BROWN DOG TICK IN 1960. TICKS (A MONOGRAPH OF THE KEY WEST, FLORIDA (ACARIÑA, IXODOIDEA). IXODOIDEA). PART V. ON THE GENERA Ent. News 24: 366-368. DERMACENTOR, ANOCENTOR, COSMIOMMA, BOOPHILUS, AND MARGAROPUS. Cambridge at the Univ. Press, London, 251 pp. 1921. THE BIOLOGIES AND HABITS OF TICKS. In: Sanitary Entomology, by Pierce, W. D., Boston, 1962. TICKS AND DISEASE. Pergamon Press: pp. 430-439. Oxford, London, New York and Paris, 445 pp.

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63 LOOMIS, E. C. 1953. AVIAN SPIROCHETOSIS IN CALIFORNIA 1915. TICKS (A MONOGRAPH OF THE IXO- TURKEYS. Amer. Jour. Vet. Res. 14 (53) : 612-615. DOIDEA). PART III. THE GENUS HAEMA- PHYALIS. Cambridge at the University Press, 1961. LIFE HISTORIES OF TICKS UNDER London, pp. 349-550. LABORATORY CONDITIONS (ACARIÑA: IXO- DIDAE AND ARGASIDAE). Jour. Parasitol. 47 , WARBURTON, C. and ROBINSON, L. E. (1): 91-99. 1926. TICKS (A MONOGRAPH OF THE IXODOIDEA). THE GENUS AMBLYOMMA. PART and BUSHNELL, R. B. IV. Cambridge University Press, London, 302 pp. 1968. TICK PARALYSIS IN CALIFORNIA LIVE- PHILIP, C. B. STOCK. Amer. Jour. Vet. Res. 29 (5) : 1089-1093. 1963. RECENT ADVANCES IN KNOWLEDGE OF LOUNSBURY, C. P. TICK-ASSOCIATED RICKETTSIA-LIKE ORGAN- 1899. THE BONT TICK: (AMBLYOMMA HEB- ISMS. Jour. Egyp. Pub. Hlth. Assoc. 38 (2) : 61-100. RAEUM (KOCH). ITS LIFE HISTORY AND 1963. TICKS AS PURVEYORS OF ANIMAL AIL- HABITS. Agr. Jour. Cape of Good Hope 15 (11): 728-743. MENTS: A REVIEW OF PERTINENT DATA AND OF RECENT CONTRIBUTIONS: In: Ad- 1904. REPORT OF THE GOVERNMENT EN- vances in Acarology, edit, by J. A. Naegele, Comstock TOMOLOGIST FOR THE YEAR 1903. Cape of Publishing Associates, Ithaca, N. Y., pp. 285-325. Good Hope. Department of Agriculture, Cape Times , HOOGSTRAAL, H., REISS-GUTFRE- Ltd., Government Printers, Cape Town, 46 pp. UND, R., and CLIFFORD, C. M. McINTOSH, A. 1966. EVIDENCE OF RICKETTSIAL DISEASE 1934. DISTRIBUTION OF BOOPHILUS ANNULA- AGENTS IN TICKS FROM ETHIOPIAN CATTLE. TUS AUSTRALIS (FULLER) IN THE UNITED Bui. Wld. Hlth. Org. 35 (2) : 127-131. STATES. Pro. Helminth. Soc. Wash. 1 (1): 22. PIERCE, W. D. 1921. DISEASES CAUSED OR CARRIED BY and McDUFFIE, W. C. MITES AND TICKS. In: Sanitary Entomology, 1956. TICKS THAT AFFECT ANIMALS AND edited by W. D. Pierce, The Gorham Press, Boston, POULTRY: In: The Yearbook of Agriculture, 1956, pp. 403-429. Animal Diseases, pp. 157-166. PRATT, H. D. and LITTIG, K. S. MAC KELLAR, J. C. and DONNELLY, J. 1967. TICKS OF PUBLIC HEALTH IMPORTANCE 1968. TICK-BORNE DISEASES OF CATTLE. Vet. AND THEIR CONTROL. Training Guide, U. S. Rec. 83 (24) : 609. Dept. Hlth., Ed., and Wei. CDC, Atlanta, 42 pp. MOREL, P. C. and VASSILIADES, G. REES, C. W. 1962. LES RHIPICEPHALUS DU GROUPE 1934. CHARACTERISTICS OF THE PIROPLASMS SANGUINEUS:ESPECES AFRICANINES. (ACA- BABESIA ARGENTINA AND B. BIGEMINA IN RIENS: IXODOIDEA). Rev. Elev. Med. Vet. Pays. THE UNITED STATES. Jour. Agrie. Res. 48 (5) : Trop. 15 (4) : 343-386. 427-438. NEITZ, W. 0. RICHARDSON, U. F. and KENDALL, S. B. 1956. A CONSOLIDATION OF OUR KNOWLEDGE 1963. VETERINARY PROTOZOOLOGY. 3. Rev. ed., OF THE TRANSMISSION OF TICK-BORNE Oliver and Boyd, Edinburgh, 311 pp. DISEASES. Onderstepoort Jour. Vet. Res. 27 (2) : ROBY, T. O. and ANTHONY, D. W. 115-163. 1963. TRANSMISSION OF EQUINE PIROPLAS- MOSIS BY DERMACENTOR NITENS NEUMANN. 1956. CLASSIFICATION, TRANSMISSION, AND Jour. Amer. Vet. Med. Assoc. 142 (7) : 768-769. BIOLOGY OF PIROPLASMS OF DOMESTIC ANIMALS. Ann. New York Acad. of Sei. 64 (2) : ROZEBOOM, L. E., STILES, G. W. and MOE, L. H. 56-111. 1940. ANAPLASMOSIS TRANSMISSION BY DERMACENTOR ANDERSONI STILES. Jour. NUTTALL, G. H. F. Parasitol. 26 (2) : 95-100. 1911. NOTES ON TICKS. Parasitol. 4 (3) : 175-182. SMITH, C. A. 1913. OBSERVATIONS ON THE BIOLOGY OF 1968. IMPORT-EXPORT REQUIREMENTS FOR IXODIDAE: PART I. Parasitol. 6 (1): 68-118. THE MOVEMENT OF EXOTIC ANIMALS. Pan Amer. Hlth. Org. Sei. Pub. 182: 183-187. and WARBURTON, C. SMITH, C. N. 1911. TICKS (A MONOGRAPH OF THE IXO- 1944. THE LIFE HISTORY OF THE TICK ORNI- DOIDEA). PART II. IXODIDAE. Cambridge at the THODOROS CORIACEUS KOCH (ARGASIDAE). University Press, London, pp. 105-348. Ann. Ent. Soc. Amer. 37 (3) : 325-335. 64 _, COLE, M. M. and GOUCK, H. K. TOVAR, R. M. 1946. BIOLOGY AND CONTROL OF THE AMERI- 1947. INFECTION AND TRANSMISSION OF CAN DOG TICK. U. S. Dept. Agr. Tech. Bui. 905, BRUCELLA BY ECTOPARASITES. Amer. Jour. 74 pp. Vet. Res. 8 (26) : 138-140.

SMITH, J. P. WALKER, JANE 1969. TRANSMISSION OF A HEMOPROTOZOAN 1955. RHIPICEPHALUS PULCHELLUS GERS- PARASITE OF THE DEER TO DOMESTICATED TACKER 1873: A DESCRIPTION OF THE ANIMALS. Amer. Jour. Vet. Res. 30 (8) : 1479-1482. LARVA AND NYMPH WITH NOTES ON THE ADULTS AND ON ITS BIOLOGY. Parasitol. 45 SOULSBY, E. J. L. (1-2) : 95-98. 1968. HELMINTH, ARTHROPODS AND PRO- 1957. RHIPICEPHALUS HUMERALIS RONDELLI TOZOA OF DOMESTICATED ANIMALS (MON- 1926. Parasitol. 47 (1-2) : 145-152. NIG). 6th ed., Williams and Wilkins, Baltimore, 824 pp. 1961. SOME OBSERVATIONS ON THE CLASSI- FICATION AND BIOLOGY OF TICKS BELONG- STRICKLAND, R. K. and GERRISH, R. R. ING TO THE GENUS RHIPICEPHALUS, WITH 1964. DISTRIBUTION OF THE TROPICAL SPECIAL REFERENCE TO THE IMMATURE HORSE TICK IN THE UNITED STATES, WITH STAGES. E. Afri. Med. Jour. 38 (5) : 232-238. NOTES ON ASSOCIATED CASES OF EQUINE PIROPLASMOSIS. Jour. Amer. Vet. Med. Assoc. 1962. NOTES ON THE COMMON TICK SPECIES 144 (8): 875-878. OF EAST AFRICA. Rep. E. Afr. Vet. Res. Org., 23 pp. 1965. COLLECTIONS OF DERMACENTOR PARU- MAPERTUS FROM CATTLE. Jour. Parasitol. 51 WILKINSON, P. R. (6) : 1000. 1953. OBSERVATIONS ON THE SENSORY PHYSIOLOGY AND BEHAVIOUR OF LARVAE TÄTE, H. D. OF THE CATTLE TICK, BOOPHILUS MICRO- 1941. THE BIOLOGY OF THE TROPICAL PLUS (CAN.) (IXODIDAE). Austral. Jour. ZooL CATTLE TICK AND OTHER SPECIES OF TICK 1 (3) : 345-356. IN PUERTO RICO, WITH NOTES ON THE EFFECTS ON TICKS OF ARSENICAL DIPS. 1964. PASTURE SPELLING AS A CONTROL Jour. Agri. Univ. Puerto Rico 25 (1) : 1-24. MEASURE FOR CATTLE TICKS IN SOUTHERN QUEENSLAND. Aust. Jour. Agri. Res. 15: 822-840. THEILER, A. 1911. DISEASES, TICKS, AND THEIR ERADICA- 1968. PHENOLOGY, BEHAVIOR, AND HOST- TION. Agr. Jour. Un. S. Afr. 1 (4) : 491-508. RELATIONS OF DERMACENTOR ANDERSONI STILES IN OUTDOOR "RODENTARIA", AND IN THEILER, GERTRUD NATURE. Cana. Jour. Zool. 46 (4) : 677-689. 1943. NOTES ON THE TICKS OFF DOMESTIC and LAWSON, J. E. STOCK FROM PORTUGUESE EAST AFRICA. 1965. DIFFERENCE OF SITES OF ATTACH- Estac. Anti-Malarica, Lourenco Marques, 55 pp. MENT OF DERMACENTOR ANDERSONI STILES 1952. STANDARDISED TICK NAMES FOR SOUTH TO CATTLE IN SOUTHEASTERN ALBERTA AFRICA. Jour. S. Afr. Vet. Med. Assoc. 23 (1): AND IN SOUTH CENTRAL BRITISH COLUMBIA, 43-45. IN RELATION TO POSSIBLE EXISTENCE OF GENETICALLY DIFFERENT STRAINS OF 1959. TICKS: THEIR BIOLOGY AND THEIR TICKS. Cana. Jour. Zool. 43: 408-411. DISTRIBUTION. Jour. S. Afr. Vet. Med. Assoc. 30 (3) : 195-203. WILSON, S. G. 1946. SEASONAL OCCURRENCE OF IXODIDAE 1961. A CONTRIBUTION TO THE KNOWLEDGE ON CATTLE IN NORTHERN PROVINCE, NYA- OF AFRICAN IXODIDAE: THE GENUS RHIPI- SALAND. Parasitol. 37 (3-4) : 118-125. CENTOR. Rev. Zool. Bot. Afr. 66 (3-4): 297-308. 1953. A SURVEY OF THE DISTRIBUTION OF 1962. THE IXODOIDEA PARASITES OF VERTE- THE TICK VECTORS OF EAST COAST FEVER BRATES IN AFRICA SOUTH OF THE SAHARA IN EAST AND CENTRAL AFRICA. Proc. 15. (ETHIOPIAN REGION). Report to the Dir. Vet. Inter. Vet. Congr. (1) : 287-290. Ser., Onderstepoort, 255 pp. (Mimeographed) YEOMAN, G. H. and WALKER, J. B. 1970. BIOLOGY AND CONTROL OF TICKS IN 1967. THE IXODID TICKS OF TANZANIA (A SOUTHERN AFRICA. Proc. of a Symp. at Rhodes STUDY OF THE ZOOGEOGRPAHY OF THE University, Grahamstown, Rep. of S. Afr. July 1-3, IXODIDAE OF AN EAST AFRICAN COUNTRY). 1969: pp. 17-36. Commonwealth Inst. of Ent., London, 215 pp.

65 HYPOTHETICAL MALE AND FEMALE HARD TICKS WITH KEY MORPHOLOGICAL CHARACTERS LABELED

PALPUS HYPOSTOME SEGMENT 4 SEGMENT 4 SEGMENT 3 SEGMENT 2 SEGMENTS SEGMENT 1 SEGMENT 2 SCAPULA SEGMENT 1 BAèlS CAPITULI BASIS CAPITULI CORNUA ■CERVICAL GROOVE GENITAL APERTURE EYE INTERNAL SPUR LATERAL GROOVE GENITAL GROOVE

ORNATE MARKINGS EXTERNAL SPUR SPIRACULAR PLATE ANUS ACCESSORY SHIELD DORSAL PROLONGATION ADANAL SHIELD FESTOON

LEG IV TIBIA TARSUS PULVILLUS CLAW METATARSUS

DORSUM OF MALE VENTER OF MALE

PORÖSE AREA COXA I CORNUA INTERNAL SPUR LATERAL GROOVE EXTERNAL SPUR CERVICAL GROOVE COXA II PUNCTATIONS COXA III ORNATE MARKING COXA IV MARGINAL GROOVE ANUS SPIRACULAR PLATE ANAL GROOVE

DORSUM OF FEMALE VENTER OF FEMALE

66 HYPOTHETICAL SOFT TICKS WITH KEY CHARACTERS LABELED

SUBAPICAL DORSAL PROTUBERANCE DORSUM VENTER

LATERAL VIEW

LEG TARSUS

METATARSUS TIBIA FEMUR LEG II TROCHANTER COXA

LEG ill

LEG IV

SUTURAL LINE

DISCS

DORSUM VENTER

67 DORSAL VIEW OF THE SCUTA AND CAPITULA OF SOME FEMALE IXODIDAE (HARD TICKS), SHOWING CHARACTERISTICS OF THE GENERA

SEGMENT 2

BASIS CARTULI PORÖSE AREA

- EYE

BOOPHILUS RHIPICEPHALUS HAEMAPHYSAUS

SEGMENT 2

DERMACENTOR AMBLYOMMA IXODES

68 SCHEMATIC LIFE CYCLES AND DISEASE TRANSMISSION OF TICKS

TYPE I

Engorged Fecundated Female Drops From Host 1 x^.,^-^^ Male May Live Several More Weeks \ \ /Oviposition Begins Adults Emerge From Nymphal Skin On Host l,Reattach,^s And Mate Female Dies

Nymphs Emerge From Larval Skin On Host l,Reattachife Remain When Replete

Larvae Attack Host 1 And Remain When Replete

\ Larvae Hatch Out

This type has one host and is represented by Boophilus decoloratus, and Dermacent omit ens. The entire life cycle from larva to adult is spent on the same host. Feeding of the tick is twice interrupted for molting, but the tick remains on the same host. The possibilities for disease transmission are continuous through all the parasitic stages. Disease organisms taken up during the parasitic period either die or may be passed transovarially to be transmitted by the offspring of the tick.

Apparently some disease organisms, especially Babesia spp., may remain in the body of ticks for as many as five generations, even when fed on non-infected, non-susceptible hosts.

69 SCHEMATIC LIFE CYCLES AND DISEASE TRANSMISSION OF TICKS -Con.

TYPE II

Adults Emerge From Nymphal Skin While On Ground And Mate Without Feeding I \ / Oviposition Begins

Replete Nymphs Drop From Host 1

Second Nymphal Stage Emerges Larvae Hatch And Reattaches To Host 1

Larvae Attack Host 1 First Nymphal Stage And Remain When Replete Emerges From Larval Skin And Reattaches To Host 1

This aberrant type is found in Otobius megnini, the spinose ear tick. There is one host on which the larval and two nymphal stages feed. The adult neither attaches nor feeds. Disease organisms taken up by the larva and nymph either die during or after the parasitic period or they may remain in the tick body during transformation, enter the egg and may be trans- mitted by the offspring.

70 SCHEMATIC LIFE CYCLES AND DISEASE TRANSMISSION OF TICKS-Con.

TYPE

Replete Fecundated Female Drops From Host Adults Attack / Male May Live Several More Weeks Host 2 and Mate

Adults Emerge From Nymphal Skin • While On Ground

^ Larvae Hatch Out

Larvae Attack Host 1 Replete Nymphs And Remam When Replete Drop From Host 1 Nymphs Emerge From Larval Skin On Host 1 And Reattach

This type, found inRhipicephalus evertsi, has two hosts. The larva and nymph develop on one host. The nymph drops when replete, molts and the adult attaches to the second host. Disease organisms acquked by the immature stages either die or remain in the tick during molting and may be transmitted by the adult to the second host. Disease organisms taken up by the female either die or may be conveyed via the egg and possibly be transmitted by the offspring. 71 SCHEMATIC LIFE CYCLES AND DISEASE TRANSMISSION OF TICKS-Con.

TYPE IV

Replete Fecundated Female Drops From Host 3

Adults Attack Host 3 And Mate Male May Live Several More Weeks

Adults Emerge From ^ Oviposition Begins Nymphal Skin While On Ground

Female Dies Replete Nymphs Drop From Host 2

Nymphs Attack ^ Host 2

Nymphs Emerge From ^ Larval Skin While On Ground Larvae Hatch Out Replete Larvae / Larvae Attack Drop From Host 1 Host 1

This type, the most common, is found in Dermacentor variabilis, Amblyomma variegatum, and most other species of hard ticks. These are the so-called "three-host ticks". The larva attaches, engorges, drops from the host and molts; the nymph reattaches to the same or another host, engorges, drops from the host and molts; and finally, the adult reattaches to the same or another host, engorges, and drops from the host. Therefore, disease organisms taken up by the larva, if able to survive the transformation, may be transmitted to the host of the nymph. Organisms taken up by the nymph which remain in the tick during molting may be transmitted to the host of the adult stage. Disease organisms acquired by the adult either may be passed transovarially to be transmitted by the offspring, or they die v^ithin the tick without infecting the next generation. 72 SCHEMATIC LIFE CYCLES AND DISEASE TRANSMISSION OF TICKS-Con.

TYPEV

Male Lives On Oviposition Begins

Adults Attack Several Hosts Over A Period Of Time. Fecundated Engorged;^^L~ Females Oviposit Each \v^\ Time ^ Larvae Hatch Out ^ Female Lives On ^ —- Larvae Attack "^ Hostl

Replete Larva Drops From ^ Host 1 First Nymphal Stage Emerges From Larval Skin Adults Emerge After Several Nymphal Molts

The Several Nymphal Stages Attack Hosts Over An Extended Period

This type is found in various species of the soft tick genera Argas and Ornithodoros. There is one larval host, several nymphal and several adult hosts. Only the larva remains on the host to feed for any length of time. Both the nymph and adult are rapid and repeated feeders. The female usually lays a small batch of eggs after each feeding. If able to survive in the tick, disease organisms taken up by any of the parasitic stages may be transmitted to subsequent hosts or may be passed transovarially to the offspring. 73 c >

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