Colorado

University service in Cooperative Extension ACTION HO. 5.517

Horse arthropod pests: characteristics and management Ann Swinker and FrankPeair s

Flies, gnats, mosquitoes, bots, lice, ticks, mites and blister beetles are the most important _ A. HOUSEFLY arthropod pests of horses in Colorado. 5, HORN FLY Insects can cause the horse to becom\ e nervous . C. STABLE FLY D. MAGGOT FROM and interrupt performance. D. MANURE Removal and proper management of manure is a key to managing several horse pests. Figure 1. ing site for the mosquito. Free standing water is a common aquatic breed- ducts of the eyes, around the nose or on wounds and cuts. Both species breed in freshEnvironmental, animal manure. biological and chemical control Stable fly (Figure 1). The bite of the small gray- ish-black stable fly is painful. It pierces the skin and methods combined work best to successfully Themanag importante Insect pestsarthropod. pests of horses in Colo- suckseggs bloo ind pilesas a offoo decayingd source vegetation. The stabl suche fly as laygrasss it s rado are: flies, gnats, mosquito, bots lice, ticks, mites clippings, manure and urine, contaminated hay and generallyand blister affect beetles. horses Arthropods directly that or feed indirectly. on blood Direct wet feed. House fly, face fly and stable fly can all transmit effects on the host areattribute dt o the pest's pres- disease and cause organisms and the parasite ence and physical nuisance. Bothersome insects can Habronema (stomach worms) to infect horses. In- cause the animal to becomenervou s and interrupt fected flies deposit stomach worm larvae in open performance. Nuisance pest s can cause the horse to creasedstomp, rub stress and load constantly can quickly switch compromise its tail, the the in- wounds that result in a lesion similar in appearance ivermectinHorninfection.withoutto Summer fly maturing (Figure Habronemiasis Sores. dewormer. 1). andThese This cause larvae verycan inflammation be small remain controlled (one-half in theand with wound the healthof pathogens, of an animal. disease-producing Indirect effects organisms. are transmission Blister sancesize of to the horses house pastured fly) fly withsucks cattle. blood Horn and isflies a nui- feed while hanging downward on the sides and legs of beetles do not attack horses, but they are toxic to horses

and can contaminate alfalfahay . Management of these insects is different from otherhors e pests in that it requires modification of alfalfaproductio n practices.

Flies (See Service in Action sheet 5.502, Flies in the home). 'Ann Swinker, Colorado State University Cooperative Extension horse specialist and assistant professor, Face fly and house fly (Figure 1). These flies are animal sciences; and Frank Peairs Cooperative non-biting, annoying small black flies. Face flies Extension entomologist and associate professor, closely resemble the common house fly, but are more entomology (revised 6/92) persistent pests of animals. They feed on the tear Colorado State University Cooperative Extension,1992 .

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Kenneth R. Bolen, director of Cooperative Extension, Colorado State University, Fort Collins, Colorado. Cooperative Extension programs are available to all without discrimination. To simplify technical terminology, trade names of products and equipment occasionally will be used. No endorsement of products named is intended nor is criti- cism implied of products not mentioned. Gastrophilusspecies . Bot fly species vary in where the eggsar e on the horse and the manner in which the eggs hatch. Ingeneral , the bot fly lays its eggs on the forelegs, shoulders, and lips of the horse during the summer and fall months. The location where the eggs are laid describes the three species: common botfly, chin bot flyan d nose bot fly. The eggs hatch when the horse licks and rubs them. Once in the mouth, the snail bots burrow into the gums and tongue where they remain for about one month and then migrate into the stomach. Upon entering the stomach, the larvae attach themselves to the A. BITING LOUSE mucus membrane and remain there for the next B. SUCKING LOUSE eight to 10 months. They detachthemselve s in the spring and pass through the feces. Once Figure 2. outside the host, the larva pupates and a mature fly emerges after a period of four to sixweeks . The developcattle in manure.an d horses. The larvae of this flyfly also mates, and the adult female lays its eggs on the horse and the cycle beginsove r again. The flies dono t bite, but egg-laying is annoying to the Horse fly and deer fly. The female horse fly and deer flyattac Khorses . Their bite is extremely horse. The principal damage caused by the bot is painful and causes a flow ofbloo d that attracts to the stomach lining. In extremecases , bots can house flies. The horse fly is plentiful in Colorado cause a stomach rupture or fatal colici f they and a real NUISANCE. Deerflies h ave yellowish-block the stomach valve to the small intestine. orange and black-body markings, picture-type Lice (Figure 2). Lice are normally species- wings and are smaller than horse flies. Horse flies specific ectoparasites of mammals. The horse are vectors of equine infectious anemia. The flies sucking louse, Haematopinus asini, feeds on lay their eggs in danp or wet soil near streams, blood. Lice are seen on the head, neck, manean d irrigation ditches or lakes. Within one week, larvae tail of the horse during winter and early spring. grown adult fly. hatch and Adultsemerge and later nymph in thestages season can beas seen the moving full through the hair; the egg or nit stage attaches to Black fly. This tiny (2 to 5 mm), humpbacked the hair. Lice produce several generations per fly can congregate in tremendous numbers around horses, causing extreme annoyance and year and can complete a life cycle in three weeks. The horse biting louse, Bovicola equi, also will infest the horse. They feed on the epidermal skin itching. These flies feed most commonly inside the ear, but also are found on the andhead abdomen, neck, ofches thet horse. Thetissue black sfly an bited secretions . Poultry lice have occa- sionally infested horses. Infested horses rub, bite causes potential hemorrhage anLarvaed blood developy incrusts fast moving. rivers and streams. themselves, stomp and exhibit extreme annoy- ance and discomfort. Gnat (biting mides or small flies, 0.6 to 5.0 mm. Two generaTick. Culicoides In the and United Leptoconops States, horses are serve as a major pests to horses. They have a painful bite and primary host for two species of ticks and a sec- ondary host of 14 other species. Heavy tick may cause hypersensitivity "sweet-itch" along the base of the mane and tail, and overburden the swithers, can resul chestt i n general unthriftiness, anemia and susceptibility to disease. Ticks are and facial areas. Lesions consist of self-inflicted hair vectors of disease such as Lyme disease found in many Eastern states. loss and excoriations with crusting. Larvae develop in Mosquito.aquatic habitats TheseMite. andinsects Thisdecaying feed very on vegetation horsessmall inparasite andgreat manure. is fairly uncomm- thatmon affect to horses. horses are However, sarcoptic mange the two mite forms of mites numbers, can produce significant blood losses and (burrows into the epidermis) and the psoroptic annoyance. Skin eruptions can appear on horses mange mite (lives on the skin surface). Both feed on skin and tissue fluids. Symptoms are irrita- bitten by mosquitoes. Mosquitoes also transmit tion, itching and scratching. equine infectious anemia (EIA), eastern equine Management encephalities (EEE), western equine encephalitis (WEE) and Venezuelan EQUINE ENCEPHALITIS (VEE). Vaccines are available for EEE, WEE and VEE. A combination of several control methods Mosquitoes reproduce in large numbers worin standingk best to successfully manage insect pests. water found in marshes, irrigated pastures, aban- Environmental sanitation. Removal and doned tires and old feed pans. propeMany rspecies managemen can fly t of manure is a key to man- several miles from their breedingagemen sites fort of feeding. several horse pests, including face flies and horn flies. Stable flies and house flies (See 5.526, Mosquito management). breed in mixtures of manure, spilled feed and Bot fly (Gastrophilus). Three species of bots bot is the larval stage of the horsaree considered bot fly, serious pests of U.S. horses. The particularly the manure breeding flies. These are quite effective under some conditions, but none have been tested rigorously for use in Colorado. Chemical control. Chemical control is the use of chemicals (pesticides) to reduce pest popula- tions orrepe l economically important species of arthropods. The correct identification of the pest species is important in order to use the right product toeliminat eth e pest. Before using a pesticide, read the label and understand the directions for • Figure 3, A. Black blister beetle, Epicauta pennsylvanica: proper preparation and application of the insecti- B. Threestriped blister beetle, Epicauta lemniscata; cide for a specific pest. Follow all directions and and C. Spotted blister beetle, Epicauta maculata. precautions. decaying bedding around the barn. To help There are many insecticides registered for control eliminate fly breeding areas, spread the manure of horse pests. Since registrations change rapidly, regularly and prevent accumulation of other specific products are not mentioned in this fact wastes. Several pesticides can be used on manure sheet. Good sources of up-to-date insecticide regis- pits to prevent maggot development. trations for horses include Colorado State University Cooperative Extension county offices, the Nebraska Free standing water found in puddles, tires and Cooperative Extension publication, Nebraska irrigation ditches are common aquatic breeding sites Management Guide for Control ofArthropod Pests of for the mosquito. Develop drainage systems to Livestock and Horses, and the Texas Agricultural prevent standing water in irrigated pastures and Extension Service publication, Suggestions for irrigation systems. Eliminate other areas where Managing External Parasites of Texas Livestock and water accumulates. Containers that hold water for Poultry. long periods of time should be removed or drained. Clean rain gutters to permit the free flow of water. While it is not important to be aware of individual Slope corrals and paddocks to permit proper drain- active ingredients of horse pesticides, it is important age. Control weeds along ditch banks for free water to be aware that these ingredients can be divided flow. into three classes: Pyrethroids (cypermethrin. fenvalerate, permethrin, resmethrin, tetramethrin, s- Vegetation management around horse facilities is bioallethrin, sumethrin), Organophosphates important. Several fly species prefer or require (coumaphos, dichlorvos, malathion, shaded areas for resting sites during hot periods of tetrachlorvinphos), and Organochlorines (lindane, the day. To help reduce fly problems, eliminate or methaxychlor). Insecticide resistance is becoming a mow weeds and other plants that might provide very serious problem in livestock arthropods. Resis- shaded resting sites. To control tick populations, tance tends to develop by class rather than by eliminate brush through cutting or burning. Pasture individual product. If resistance seems to develop, rotation will help control certain species of ticks. switch to a product in another class. Also, rotate Stabling horses during daily peaks of fly activity from insecticide class to insecticide class to avoid the can provide some relief. Screening stable windows development of resistance. and doors will reduce interior fly activity. If stabling Pesticide applications to protect horses can be is not feasible individual protection devices such as divided into area sprays, residual premise sprays ear nets, face masks and repellant tags or tapes can and direct animal treatments. Apply pesticides be considered. Owners should perform seasonal directly to horses via sprays, sponges, roll-ons, slow- practices such as castration when the fly population release plastic strips, pastes, gels, and feed additives. is smallest (i.e., winter) and the wound has the least exposure to flies. • Area treatments: Mist blowers, as well as hydraulic sprayers, foggers and aircraft, can be Biological control is the use of other organ- used to apply fast-acting short-lived insecti- isms (pathogens, parasites, predators and com- cides to provide immediate relief from nuisance petitors) to reduce populations of arthropod files. Fine droplets are dispensed into areas pests. These methods can take several months or occupied by flies, killing them on contact. This years before any results can be seen. Several method is very efficient in terms of time and labor, successes have been observed with biological but has no long term effect on fly populations. control of mosquitoes: • Premise treatments with residual insecticides • Biological insecticides such as Bacillus to provide fly control for one to two weeks. Apply insecticides as a thuringiensiscoarse spray var. undeisraelinsi r low pressurs (available e under to shaded, fly restinseveralg areas trade. Hous e names),flies are mosa t bacteria, can be used to treat free standing water for immature commonly found under eves, and on walls, rafters mosquitoes and to treat running water for and ceilings. Stable flies, on the other hand, immature black flies. commonly rest outdoors, on. the shady side of • Mosquito fish or top feeding minnows (Gambu- building, windbreaks and other vegetation. Be sia) are effective predators of mosquito larvae. careful not to contaminate feeders, water bucket Several commercial enterprises offer other or equipment with pesticides. Remove horses from beneficial insects for control of livestock pests. barns before spraying. With some sprays, the horse important to control flowering weeds and choose the must remainou t of the barn for a short period of time. best harvest equipment that gives the beetles the best « Direct home treatments. Apply mist sprays that chance of survival. Recent research at Kansas State require a fine mist with either a small mist blower or a University has shown that self propelled swathers, hand-held mist sprayer. One of the easiest methods to without conditioning rollers but with windrowing spray a few horses for fly and mosquito control is attachments, are safer than mower conditioners and a small, compressed air sprayer. The apparatus is sicklebar mowers. Even with the conditionerless quiet and does not frighten the animals. If you have a swather, avoid hay from the ends of the fields where horse that is frightened by sprays, wet a sponge, cloth the machinery is turned around and beetles may be or mit and wipe the solution on. Not all animal crushed by the tires. insecticides are suitable for use on horses, so be sure 2. Chemicalcontro ltreat sth e crop just prior to harvest that horses are specifically mentioned on the label. to eliminate beetle activity during harvest.Ther e is not much data on blisteBlister beetlr e control. Most recommen - Beetle (Figure 3) gets its name from the fact that they produce a chemical, cantharidin, that can raisdatione s seem to be based on preharvest intervals. blisters on the human skin. Cantharidin, taken inter- Refer to the Colorado Pesticide Guide—Field Crops for nally, also is toxic to a number of mammals, especially future information on alfalfa insecticides. horses. Blister beetle poisoning has become a problem 3 Select hay sources that have a low likelihood of for horse owners in recent years because of a combina- blister beetle contamination. First cutting hay is tion of blister beetle biology and alfalfa harvest practices. the least likely to have beetles. Hay from third and Blister beetles are common in Colorado, with more fourth cutting is the most likely to have beetles. than 100 species known to occur in the state. The larval Hay from alfalfa fields located near rangeland also stages of our largest group, Epicauta, are unusual in that is relatively risky. they feed on grasshopper eggs. Figure 3 shows some of Pest Management Recommendations the common Colorado Epicauta species. Because of the larval feeding habit, blister beetles tend to occur in areas Face Fly Manure management, screening of stables, vegeta- tion management, premise sprays, repellents, horse- where grasshoppers are common and more numerous sprays. when grasshoppers are abundant. Adult blister beetles House Fly Manure management, screening of stables, vegeta- feed on flowers of several crops, including alfalfa. They tion management, premise sprays, repellents, horse also tend to feed to groups or swarms. sprays; stable or provide shade to horses during Blister beetles are concentrated in alfalfa hay during peak fly activity periods. harvest when swarms are trapped by harvest equipment Stable Fly Manure management, screening of stables, vegeta- and crushed by the conditioners and tractor tires before tion management, area sprays, premise sprays, repellents, horse sprays; stable or provide shade to they can escape. While many believe that the presence of horses during peak fly activity periods. a single beetle in a bale of hay poses a health hazard to a Black Fly Repellents, horse sprays, keep horses stabled or horse, the risk is not quite that great and the risk varies provide shade during peak fly activity periods. with the type of blister beetle. Although cantharidin is Provide individual horses with car nets or applica- extremely toxic to horses, blister beetles are small and Deertions Fliesof petroleu & m jelly to the inside of the ears. individually do not contain a lethal dose. Colorado State University measured the cantharidin levels in several Horse Flies Repellents, horse sprays. blister beetle species and estimated their relative risk to Mosquitoes Larval management by elimination of sanding water horses of different body weights. Based on average and approved larvicides. Minnows (fish) where cantharidin content, and assuming the presence of equal standing water cannot be drained or treated. numbers of male and female beetles, the lethal dose of Repellents. Encephalitis vaccines the species would be as follows: Bots Consult your veterinarian for drugs available for internal parasite control. Remove (by clipping or scraping) the yellowish bot eggs from the horses hair before they hatch. Warm wafer will cause eggs to Number of blister beetles lethal to a horse hatch, allowing small larvae to be killed before they weighing: enter the mouth. Species 275 lbs 550 lbs 825 lbs Gnats Repellents, horse sprays, fans placed in stalls. Apply corticosteroid creams to the allergi1100c skin lesions. Black blister beetle 550 1700 MitesLabele dpesticide s are effective in controlling mites 175 Spotted blister beetle 520 345 and quarantine affected horses. Threestriped blister beetle 40 90 120 LiceAn imal sprays can easily control lice. Do not stable Clearly, different blister beetles species pose horses near poultry. Good grooming is also impor- different risks to horses. Take these differences into tant. account in management decisions. Ticks Pasture mowing and brush removal. Rotate to pastures with lower tick populations. Repellents There are several components of blister beetle man- and/or residual insecticides. agement: cultural practices, chemical control and selection ofalfalf a hay sources. 1. Cultural practices involve timing of cutting and modification of harvest equipment.Sinc e blister beetles are attracted to flowers, cut the crop prior to bloom to reduce their presence in hay. It also is