Biting in Orthoptera and Their Alijes

Biting in Orthoptera and their alijes

S. K. GANGwERE. (Detroit) 1 •

Orthoptera of some subfamilies bite when handled carelessly, while those of other subfamilies rarely do so. This behavior has not been reviewed, and the little that is known about it is recorded perfunctorily within reports on other topics. It is probably more common than is indicated by its scant literature ; those who are sufficiently trained in entomology to report defensive biting are expert in handling the insects and not likely to be bitten. The vast majority of bites, therefore, go unrecorded. 'Whatever the extent of biting-, it is of interest both in terms of its possible biological significance and because it hurts. In the course of my studies on the mouthparts and feeding behavior of Orthoptera, I have, on occasion, been bitten or threatened by my test animals. Other entomologists have kindly informed me of similar experiences with various species, and I have carefully noted all records that I have found in the literature. This information is brought together in the following report, in which the biting behavior of the major groups of Orthoptera is assessecl—admittedly on the basis of insufficient information. Inasmuch as even closely related species may differ their tendency to bite, such generalizations as are made must he quali- fied. Nevertheless, on the whole the members of each group exhibit fairly consistent patterns of biting, 'which can be related to their mode of life, food habits, and mandibular structure.

SURVEY OP BITING IN 'NIE GROUPS AND SPECIES.

Blattoidea. I have neither encountered literature records of defensive biting by cockroaches, nor have I suffered personal experiences of

1 Contribution No. 155 from the Department of Biology, Wayne State Uni- versity, Detroit, Michigan, 48202, U. S. A.

Eos, XLII (1966). 364 s. K. GANGWERE

that type. My past research with these secretive orthopterans has been based largely on the wild genera Ectobius, Parcoblatta, and others of small size and innocuous habits ; they would not be expected to bite. I have done more limited studies with Blaberus, Blatta, Byrsotria, and Periplaneta, four domestic genera of large size. The results here, too, were negative, even in the case of P. australasiae, which I deliberately prodded in an unsuccessful attempt to induce biting. W. J. Arnold, a cplleague who specializes in blattid histology, has had somewhat different experiences. Arnold reports (personal communication) that he is often rasped by the mandibles as he handles Blatta, Blaberus, and Periplaneta, though their bite is unsuccessful, as they cannot grasp the skin. He has not detected this habit in Parcoblatta. There is a second kind of biting by cockroaches that is actually a type of feeding behavior. It is the occasional gnawing of sleeping or incapacitated adults or helpless infants, -which behavior was reviewed by Roth and IWillis (1957). Their references document the fact that, in cases of heavy infestation, toenails, fingernails, and calluses of living humans may be nibbled ; open wounds and blisters attacked ; the thin skin of the face, ears, and other places bitten ; and even the dead strip- ped of flesh. Manto idea. The few observations I have made on mantids enable me to say only that Ameles and certain other genera do not bite in res- ponse to repeated prodding. Crane, who published on the mantids of Trinidad (1952), has more extensive information. She found one type of defensive behavior (viz., aggressive attack) that is of interest. Ag- gressive attack does not involve biting, but merely a lightning-like rake with the fore legs, that are extended, boxer-like, from their flexed Po- sition against the prothorax. Actual biting, when it occurs, comes as a last resort when the insect is teased repeatedly or seized by the head. Phasmoidea. I have investigated comparatively few species of walking sticks, chiefly of the genera Diapheromera and Leptynia, none of which has attempted to bite even when prodded deliberately. This negative evidence, together with phasmids' mimicry, their autocatalepsy, the specialized nature of their mouthparts, and the lack of biting records in the literature, indicate that stick insects do not bite. Acridoidea. Biting is uncommon in most grasshoppers. I know of no literature records of biting by Truxalinae 2, or slant-faced grass-

2 Including the Oedipodinae, whose species most authorities now place under the Truxalinae.

B1TING IN ORTHOPTERA AND THEIR ALLIES 365 hoppers, and in the course of studying many species of them in nature do not recall ever having been bitten. I have studied numerous species of Cantantopinae, or spine-breasted grasshoppers, most of which proved innocuous—so much so that not even the most injudicious handling elicited a bite; in contrast were a few species that tend to nip, though they are never aggressive. Based on my records and those of some colleagues, IVIelanoplus bivittatus, M. confusus, M. d. differentia- lis, and Schistocerca lineata are examples. Their bite, a pinching or rasping, is not capable of drawing blood but can be the object of discomfort. I have yet to study in nature a member of the Romaleinae, or lubber grasshoppers, but am assured by the orthopterist D. C. Rentz that these ponderous insects do not bite. He reported his continuing astonishment (in litt.) that the large-bodied genera Brachystola, Draco- tettix, and Romalea never attempt to bite when collected. Much the same can be said for the Pamphaginae, another group of large, lubberly grasshoppers, several genera of which I have studied personally. Grasshoppers' attraction to the human skin and articles soiled by it is a matter of record. This behavior may be more complicated than it appears superficially. The skin may not be the actual object of attack ; its water, salts, and oils sometimes seem more attractive than it does. Salt seems particularly important, as discussed by Morse (1930). Whatever the attractant, the allure that human skin holds for grasshoppers becomes pronounced when the insects are in outbreak populations, the weather is hot and dry, and the human to be bitten is asleep, incapacitated, or perspiring profusely. The nipping, under conditions outlined immediately aboye, seems more a case of attempted feeding than of biting. An example is found in a letter by Gen. A. Sully, published in the St. Paul Press, Minnesota, U. S. A., June 21, 1865. He wrote : "A soldier on his way here lay down to sleep in the middle of the day on the prairie. The troops had been marching all night. His cornrades noticed him covered ,with grasshoppers, and woke him. His throat and wrists were bleeding from the bite of these insects." Some other reports are even more fantastic. Whiting (1915) reported from the Near East a documented case involving a peasant woman and her child. The woman had placed her tiny baby in the shade of a tree while vainly attempting to divert from her orchard an oncoming horde of locusts. Returning later, she found the child covered with locusts and its eyes consumed from their sockets. Another example, a supposedly accurate account of the death of the

366 S. K. GANGWERE

eminent entomologist M. Kunckel Herculais, was described dramati- cally in a reputable scientific journal (Anonymous, 1891): "While exa- mining a deposit of locusts' eggs at the village of Sidieral he (M. Kun- ckel Herculais) was overcome with fatigue and the heat, and feil asleep on the grouncl. While sleeping he was attacked by a swarm of locusts. On awakening he struggled desperately to escape from the flood. He set fire to the insect-laden bushes near him, but all his efforts proved ineffectual, and, when finally the insects left the spot, his skeleton was founä, together with his hair, beard and necktie. The rest of him had Leen entirely devoured." The circumstances of his death, as outlined aboye, were questioned in certain other reports (Anonymous, 1891a). lettigonoidea. Almost all subfamilies of katydids bite and some are biters par excellence. Two subfamilies, the Phaneropterina t and Pseudophyllinae, are perhaps exceptions ; negative results from my field work and a lack of biting records from my colleagues and the literature suggest that they do not bite to any great extent. Even so, at least two genera with which I am acquainted, Pterophylla and Lea, remain upen to question because of their strong mouthpart structure. I have investigated nearly a dozen species of Conocephalinae belonging to two genera, Conoce phalus and Orchelimum. In the course of studying them I have yet to be bitten but recall having been threatened by Orchelimum spp. on several occasions. T. H. Hubbell informs me (personal communication) that Conoce phalus sometimes bites and Odon- toxiphidium and Orchelimum often do so. Rehn and Hebard (1907) reported that une species of Orchelimum clings so tenaciously when it bites that its head may be pulled from its body without causing rela- xation of its jaws. There is a habit related to biting that I have often observed in Cono- cephalus spp. The meadovv- katydids in question are attracted to the human skin, the surface of which they assiduously explore with their mouthparts whenever an opportunity is presented. In doing so they carefully work along the surface, rasping gently with the mandibles and "sponging" with the galeae, but causing no discomfort. The behavior is probably associated with obtaining perspiration, skin oils, or salt. It is not true biting. I have no personal records of biting by Copiphorinae, or cone-headed katydids, though I have worked extensively with several species of Neoconocephalus and with one of the European genus Homorocoryphus. The most closely related behavior that 1 have found is the frequent ten-

BITING IN ORTHOPTERA AND THEIR ALLIE,S 367 dency of N. ensiger, when handled, to bare its wicked-looking mandibles in a threatening manner. Several biting records of other investigators show that Belocephalus and some Neoconocephalus do indeed bite, and in at least two instances the wounds inflicted were sufficiently severe to cause bleeding. So formidable are the jaws of cone-heads that this demonstration of their biting prowess is not unexpected ; biting in the group as a whole is probably common. The katydid subfannlies Decticinae, Ephippigerinae, Listroscelinae, and Tettigoniinae include species that, according to my records and the literature, bite viciously. The subfamilies Hetrodinae and Saginae are said to include biting species, and my experience with one species of Pycnogastrinae indicates that group, too, bites. Some Saginae and Decticinae are reputed to bite so severely as to cause bleeding. A typi- cal bite was described by Tinkham (1944), who discussed graphically the capture of the decticine Capno botes bruneri: "'Ehe evening meal had just been finished and darkness was fast approaching when some `tzwks' sounded from the tops of nearby towering 'Western Yellow Fi- nes. As the song 'was new to the writer, it 'was decided to make the ascent despite the setting and the arduous task facing the would-be hunter About fifty feet up the katydid, singing in the top of the pine, heard the bunter and stopped singing, whereupon the hunter sat on a limb a quarter of an hour for the song to recommence Suddenly, when the song seemed to be immediately overhead, it stopped ... There in a clump of long pine needles perched the troubador ... The pine top was gently swaying as the hunter wrapped his legs around the slender trunk for support. Then with the flashlight in his left hand, the hunter made a sudden grab at the katydid. As he extricated the katydid from the pine needles the creature responded with a vicious bite that caused an ouch' to resound through the tree-tops, and as the katydid chewed away on finger tissue the flashlight was replaced and the cyanide jar obtained and the lid unscrewed with the fingers of one hand holding it. Finally the katydid was ensconced within the jar and, trembling with the strain and excitement, a feeling of great relief carne when two hands again gripped the tree." The attack of these large, fiercely biting kaydids is usually defensive; they bite only when teased repeatedly or handled bodily. In at least one group, however, there are species so pugnacious as to go to the offensive before they are touched. That group, the Listroscelinae, includes a number of species of Neobarrettia formerly included in the

368 S. K. GANGWERE

genus Rehnia. Their aggression has been vividly described by Tink- ham (1944), who wrote concerning Rehnia cerberus Neobarrettia spinosa): "Approaching the specimen I planned to catch it in my fingers for it was about five feet off the ground, and I did not have a net. When my hand was slowly approaching and about six inches away Rehnia suddenly assumed an interesting and menacing attitude. Its spiny forelegs were held high aboye its head, mantid-like, its antennae held back and its beautiful mottled pale green and black wings spread fan-wise to each side and its mandibles were bared. Suddenly without warning it gave a few tszicks', jumped to the end of my finger and gave me a vicious nip, then quickly dropped to the ground and crawled under a cactus plant growing in a clump of mesquite. Such aggressi- veness took me completely by surprise as it was all over in a few se- conds. The mouse had attacked the elephant, a katydid a man a thous- and times his size." Gryllacridoidea. The gryllacridids include both biters and non- biters. The stenopelmatine genera Cratomelus, Stenopelmatus, and others nip severely if given a chance, whereas the docile rhaphidopho- rine Ceuthophilus and its close relatives never even threaten to bite (Hubbell, personal communication). Grylloidea. There is comparatively little information concerning biting in crickets, and evidence bearing on the subject is conflicting. The paucity of records suggests that crickets are not particularly dis- posed toward biting, but the pugnacious nature of certain crickets —that makes possible the well-known cricket fights of the Orient— indicates that they do bite. I have comparatively little personal information to offer. I have observed Gryllus pennsylvanicus individuals fighting over food (and biting one another) in nature, though this is not Liting of man. I have also induced, by teasing, weak biting in Acheta domesticus. Howard and Marlatt (1902), also discussing A. domesticus, reported that it is very pugnacious and bites vigorously when captured. My colleague L. Levine, engaged in research on cricket physiology, does not feel that Acheta is aggressive, though he admits that the insect bites feebly (personal communication). He finds that Gryllus pennsylvanicus bites and is more aggressive that is Acheta. Two other species of Grvllus, G. campestris and G. bimaculatus, are well-known for their biting (E. Morales Agacino, personal communication). At least one cricket, Brachytrypes membranaceus, is known to bite so severely as to draw blood.

BITING IN ORTHOPTERA AND THEIR ALLIES 369

MAJOR TYPES OF DEFENSIVE BITING.

The Orthoptera and their alijes exhibit several degrees of biting or its lack. The folluwing is an artificial classification of the insects in terms of their biting behavior a. Species That Do Not Bite. Some species never attempt to bite even when threatened, prodded repeatedly, or handled roughly ; they merely seek shelter. Examples of these docile Orthoptera are found among the camel crickets, the walking sticks, the truxaline and many cantantopine grasshoppers, and various small species belonging to a number of subfamilies. b. Species That Rarely or Occasionally Bite IWhen Abused. These insects bite sometimes —often as a last resort— when handled either roughly or repeatedly. Certain gryllines and cantantopines are examples. c. Species That Customarily Bite When Abused. Insects of this type bite whenever the collector inadvertently exposes his flesh to attack. Examples are found among most katydids ; they bite viciously, and occasionally (as with the sagines and certain decticines) they cause bleeding. d. Speeies That Attack and Bite When Threatened or Abused. At least one genus, Neobarrettia, includes katydids that have a stylized display posture. The effect is impressive and sometimes sufficient to intimidate. If the posture does not dissuade the intruder, then the katydid leaps to the offensive, bites, and retires before its startled foe can regain composure. The attack may be from a distance of one-half foot. A similar display posture is used by mantids, but in this case it is bluff it is not usually succeeded by biting.

CORRELATIONS BETWEEN M.ANDIBULAR STRUCTURE, BITING, AND AGGRESSION.

Biting seems correlated with the degree of development of the mandibles. Those Orthoptera that seldom or never bite are rarely, if ever, aggressive, and their mandibles are most often adapted für phy- tophagy. Grasshoppers and walking sticks are examples. Even when the mode of existence is wholly carnivorous biting does not necessarily

370 S. K. GANGWERE

occur. Mantids, für example, catch and hold prey by the use of rap- tonal fore legs ; the jaws are correspondingly weak, the behavior corn- paratively non-aggressive, and biting almost non-existent. In contrast are the viciously biting katydids of such groups as the Decticinae, Lis- troscelinae, Saginae, Tettigoniinae, and others. Their mandibles —powerful organs armed 'with fang-like dentes— are used in catching prey, and their legs are non-raptorial. These groups tend toward ag- gresSion, and some are highly aggressive.

AN OVERVIEW OF BITING.

The mandibles of insects are sclerotized, opposable objects prirnarily concerned with handling food. Any rigid organ of opposable nature (including the mouthparts) is potentially capable of use in a number of \vays. The non-feeding uses of the mouthparts in one or another species include digging; chewing leaves to facilitate oviposition ; remov- ing the spermatophore ; grooming ; spreading "spit" (regurgitated croo contents) ; displaying for protection or recognition ; escaping from egg cases, exuviae, or other encapsulating structures ; sound producing ; and biting. Some of these functions (e. g., grooming) are commonly practiced but others (e. g., biting) only occasionally so. Wherever adopted, they convey to their possessors a certain selective advantage, which, in turn, can alter the course of evolution. Therein lies the significance of these habits —and that of biting. Biting has the potential of startling or of hurting the intruder to the point that it ceases or delays its attack, during which the biter is able to make good its escape. It succeeds to varying degrees, sometimes permitting withdrawal but sometimes falling short of that ob- jective. It is variously adopted in the Orthoptera, some species resort- ing to it rarely or not at all . and others regularly. It is, of course, a natural tendency that can be directed against any Opponent, whether invertebrate or vertebrate. It has here been discussed in light of a particular species of offender, man, but the conclusions drawn are ap- plicable to other organisms. It is, therefore, of more than liniited biological interest. Finally, biting is but one phase of the general defensive behavior of Orthoptera and their allies. In most of these insects the defensive behavior involves one or more methods, as follows : they "freeze" and BITING IN ORTHOPTERA AND THEIR ALLIES 371 try to take advantage of protective coloration or form ; sidle around a stem, leaf, or other object to hide ; or fly, jump, or fall to the ground in an attempt to find shelter. If caught, they kick violently with the legs (especially in the Saltatoria) and regurgitate their crop contents. Rarely they hiss, make other sounds, or release a foul-smelling subs- tance. As a last resort some species bite. Other Orthoptera rely on a more complicated defensive behavior ; they have a stylized display posture superimposed on the foregoing reflex activities preliminary to biting. 'Whatever the case, these defensive activities may well be hier- archical, each involving a given releaser mechanism. The precise nature of these mechanisms can only be surmised now, and could form the basis of a series of productive future researches.

ACKNOWLEDGMENTS.

Drs. A. B. Gurney, U. S. National Museum, Washington, D. C., T. H. Hubbell, University of Michigan, Ann Arbor, Michigan, and Sir Boris Uvarov, Anti-Locust Research Centre, London, England, kindly read the manuscript of this report and supplied additional records and references ; E. Morales Agacino, Instituto Español d En- tomología, Madrid, Spain, D. C. Rentz, University of California, Ber- keley, California, and H. 'Weidner, Zoologisches Museum, Hamburg, W. Germany, gave valuable records and information ; and many other investigators usted in Appendix I gave records and comments relative to biting. To these persons I am indebted.

References.

ANONYMOUs. 1891. A savant's horrible death. Ent. Nezeis, 2, p 122. 1891 a. Notes. Psyche, 6. p. 100.

CRANE, J. 1952. A comparative study of innate defensive hehavior in Trinidad mantids. Zoologica, 37, pp. 259-293

HOWARD, L. O. and C. L. MARLATT. 1902. The principal household insects of the United States. U. S. Dept. Agric. Div. Ent., 4 (n. ser.), 131 pp.

372 S. K. GANGWERE

MORSE, A. P. 1930. Grasshoppers vs. salt. Jour. Econ. Ent., 23, p. 465.

REHN, J. A. G, and M. HEBARD. 1907. Orthoptera from northern Florida. Proc. Acad. Nat. Sci. Philadelphia, 59, pp. 279-319

ROTH, L. M., and E. R. WILLts. 1957. The medical and veterinary importance of cockroaches. Smithsonian Misc. Coll., 134, 147 pp.

TINKHAM, E. R. 1944. Biological, taxonomic and faunistic studies on the shield-back katydids of the North American deserts. Amer. Midl. Nat., 31, pp. 257-328.

WHITING, J. D. 1915. Jerusalem's locust plague. National Geogr. Mag., 28, 511-550. • ▪

BITING IN ORTHOPTERA AND THEIR ALIJES 373

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