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ahead to set the course. Flight continues as long as the insect remains in the plume. Tsetse fl ies ( Glossina spp.) are thought sometimes to use aim-and-shoot upon takeoff, but other observations support a conven-tional optomotor anemotaxis maneuver during fl ight. Tsetse fl ies may shuttle between these two orientation strategies. Walking insects use a nonoptomotor version of anemotaxis. Upon detection of odor, the insect simply heads upwind, using simple mechanosensory input to determine wind direction.

CONCLUSION Taxes and kineses remain the principal organizing system for

understanding and investigating how insects and other organisms

12

25

65

65

0

Pulsecontact

�12

15

0

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15

0

�15

Wind

Wind

Wind

(A)

(B)

(C)

Cro

ssw

ind

dist

ance

(cm

)

Upwind distance (cm)

FIGURE 5 Top view of fl ight tracks of males of the moth Cadra cautella fl ying toward a source of a sex pheromone. The moth is traveling from left to right. The dots represent the moth’s position every 1/30th of a second. The blue line shows the time-averaged centerline of the plume. Track “ A ” shows the path of a moth after intercepting a single puff of pheromone. [Redrawn from Mafra-Neto and Card é (1994), Nature 369 , 142 – 144.] About 200 ms after inter-cepting the puff, the male surges upwind briefl y. Track “ B ” shows a male fl ying along a narrow ribbon plume of pheromone, sporadi-cally encountering pheromone. Track “ C ” shows a male fl ying along a wide turbulent plume of pheromone, encountering many fi laments of pheromone per second. [Redrawn from Mafra-Neto and Card é (1995), Physiological Entomology 20 , 117 – 133.]

“ know where to go. ” Discovering how these maneuvers work — what information is extracted, how it is processed, and the nature of guid-ance systems — remains an active area of inquiry.

See Also the Following Articles Dance Language ■ Host Seeking ■ Magnetic Sense ■ Migration ■ Monarchs ■ Pheromones ■ Tsetse Fly

Further Reading Bell , W. J. , and Card é , R. T. (eds.) ( 1984 ) . “ Chemical Ecology of Insects ”

Chapman & Hall , London . Bell , W. J. ( 1991 ) . “ Searching Behaviour: The Behavioural Ecology of Finding

Resources . ” Chapman & Hall , London . Card é , R. T. , and Willis , M. A. ( 2008 ) . Navigational strategies used by fl y-

ing insects to fi nd distant, wind-borne sources of odor . J. Chem. Ecol. 43 , 854 – 866 .

Fraenkel , G. S. , and Gunn , D. L. ( 1961 ) . “ The Orientation of Animals. Kineses, Taxes and Compass Reactions . ” 2nd ed. Dover , New York .

Jander , R. ( 1975 ) . Ecological aspects of spatial orientation . Annu. Rev. Ecol. Syst. 6 , 171 – 188 .

Kennedy , J. S. ( 1986 ) . Some current issues in orientation to odour sources . In “ Mechanisms in Insect Olfaction ” ( T. L. Payne , M. C. Birch , and C. E. J. Kennedy , eds. ) , pp. 10 – 25 . Clarendon Press , Oxford, UK .

Sch ö ne , H. ( 1984 ) . “ Spatial Orientation. The Spatial Control of Behavior in Animals and Man . ” Princeton University Press , Princeton, NJ .

Orthoptera (Grasshoppers, Locusts,

Katydids, Crickets)

Sigfrid Ingrisch Museum Koenig Bonn

D.C.F. Rentz California Academy of Sciences

O rthoptera is considered here in a restricted sense, excluding cockroaches, mantids, and stick insects, which are covered elsewhere. The Orthoptera include terrestrial insects com-

monly known as short-horned grasshoppers, katydids, bush crickets, crickets, and locusts. The adult size range is from a few millimeters to some of the largest living insects, with bodies over 11.5 cm in length and wingspans more than 22 cm. Orthopterans occur all over the world, except in the coldest areas. They are best developed in the tropics. In terms of numbers, they are among the most common insects and are an important component of the fauna in most parts of the world. The order is readily identifi ed by the characteristic hind legs developed for jumping. Tropical nights and warm summer days in temperate climate are often dominated by the songs of many spe-cies in several families. Locusts are among the world’s most important economic insects, and many species cause devastation in many parts of the world. Orthopterans are mentioned in biblical writings and in the earliest of Chinese literature. In recent times they have been important elements in the development of several fi elds of biology. Biological lifestyles in the Orthoptera include phytophilous (leaf

Orthoptera 733

living), geophilous (living on and in the ground), cavernicolous (liv-ing in caves), and myrmecophilous (living with ants). Species can be diurnal and nocturnal. Almost 24,000 species are known, but it is esti-mated that this fi gure may double when a thorough census is made of uncollected regions of the globe.

CLASSIFICATION Several disparate classifi cations of orthopteroid insects are used

simultaneously, depending on preference. There has been an overall escalation of rank of categories in recent years at and above the

tribal level. One of the extremes of these views was expressed by Dirsh, who created 10 orders from what was traditionally considered one. Kevan provides a synthesis of the classifi cations to 1982. The advent of cladistics and molecular phylogeny has spawned additional changes to orthopteroid classifi cation. The Orthoptera usually are divided into two suborders: the Ensifera (long-horned Orthoptera) and the Caelifera (short-horned Orthoptera) ( Table I ). The ensifer-ans are considered to be the more ancient group, with fossils dating from the Carboniferous, whereas caeliferans are known only from as far back as the Upper Permian ( Fig. 1A ).

O

TABLE I Some Characters Used to Separate the Two Suborders of the Order Orthoptera

Character Ensifera Caelifera

Antenna More than 30 segments Less than 30 segments Auditory structure (when present) On foretibia On fi rst abdominal tergite Alary stridutatory structures (when present) Forewings specialized with fi le and scraper Forewings modifi ed laterally and ventrally Ovipositor Elongate, sword like or sickle-shaped Short and stub-like Molting Skin usually eaten Skin never eaten

Ensifera

Caelifera

Orthoptera

Acridoidea

TrigonopterygoideaTrigonopterygidaeXyronotidae

Pneumoroidea

Pyrgomorphoidea

Tanaoceroidea

ProscopiidaeEumastacoidea

Eumastacidae

Tetrigoidea

Tridactyloidea

Hagloidea

Gryllacrididae

StenopelmatidaeStenopelmatoidea

Anostostomatidae

Lezina

Tettigonioidea

Rhaphidophoroidea

Schizodactyloidea

Gryllotalpidae

GryllidaeGrylloidea

Phasmida

Grylloblattodea

Blattodea

(A)

( )

( )

( )

( )

( )

( )

( )

( )

FIGURE 1 (A) Proposed phylogeny of the orthopteroid insects based on molecular studies. [Modifi ed combination of data from Flook et al. (1999). Syst. Biol . 48 , Fig. 2, and Jost and Shaw (2006). Molec. Phylogenet. Evol . 38 , Fig. 14.] (B) Xanthogryllacris punctipennis , an example of a gryllacridid with patterned wings. (C) Hadenoecus puteanus , a camel cricket illustrating the typical humpbacked appearance. [B and C modifi ed from “ Genera Insectorum. ” (1937). Vol. 206.] (D) Schizodactylus monstrosus , an unusual orthopteroid. [Modifi ed from Karny, H. H. (1929). Lignan Sci. J .] (E) Apote notabilis , a large North American tettigoniine. [From “ Genera Insectorum. ” (1908). Vol. 72.] (F) Henicus pro-digiosus , a wingless South African henicine. [Modifi ed from “ Genera Insectorum. ” (1937). Vol. 206.] (G) Dianemobius fascipes . [From Chopard, L. (1969). “ Fauna of India and the Adjacent Countries. ” ] (H) Oecanthus pellucens , a typical oecanthine, male. [From Chopard, L. (1943). “ Orthopt è roides de L’Afrique du Nord. ” Paris.] (I) Stolliana sabulosa , female wingless species. [From “ Genera Insectorum. ” (1916). Vol. 170.]

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FEATURES OF THE ORDER General Comments

Orthoptera have been popular subjects for the behaviorists. Much has been done of an interdisciplinary nature relating to natu-ral and sexual selection, signaling behavior, acoustic and vibrational communication, and displays.

Many orthopterans have excellent sight and hearing and are wary and diffi cult to approach. Others appear sluggish and rely on a number of cryptic strategies and distasteful properties for protection. For example, if seized, most species will kick out with their spiny hind legs and regurgitate acid contents of the crop. Because orthop-terans are fed upon by a vast number of vertebrates and many other arthropods, such behavior is not entirely successful. If a grasshopper, cricket, or katydid is seized by the hind leg, the leg will generally be lost at a point between the femur and trochanter. A number of unre-lated species will squirt or discharge repugnatorial secretions from intersegmental glands.

The majority of orthopteran species are phytophagous, feed-ing on the foliage of higher plants. A number of them feed on roots and others on fungi. Many species are predaceous, while others are omnivorous. Relatively few species have been studied for the pur-pose of discerning their feeding activities, but some are very highly specialized, feeding only on seeds, pollen, or nectar or fl owers of cer-tain plant types. The fore and middle legs are used by some preda-tors to form a “ clap-trap ” to catch unwary insects.

Orthopterans are renowned examples of forms of crypsis. They span the range resembling leaves, twigs, bark, stones, or fl ow-ers. These appearances are meant to deceive vertebrate predators. To achieve this, various parts of the body are modifi ed, and these combine with camoufl aging colors and patterns, accompanied by the appropriate behavior. Mimicry of other insects abounds in the orthopteroids. Mimicry in the nymphal stages is often based on very different models from the adults. In a few examples, males mimic a different model from females. The distasteful properties involved with aposematic coloration are exhibited in many orthopterans in a wide range of families and genera. The normally associated behavioral traits of sluggish behavior, conspicuous situations, and gregariousness are also seen. Flash or frightening colors are exhibited in a number of species. Several unrelated species in different parts of the world bury themselves in sand overnight or for short periods during the day when danger threatens. Many species overwinter in cracks or under leaves in leaf litter. A number of katydids and grasshoppers are semiaquatic. Some swim or skate over the surface fi lm, and even nonaquatic spe-cies can swim freely in midwater. These species have subtle structural adaptations for aquatic life.

The majority of orthopterans are cryptozoic, lacking bright colors and patterns. They rely on pale, drab, and dull colors to conceal their presence. Cavernicolous species have pigmentation associated with their particular lifestyle in their habitat. The more highly special-ized types lack pigmentation and have thin integument, as well as extraordinarily long antennae and long, delicate appendages. Those with extremes of structural modifi cation are types that remain larvi-form as adults, having reduced eyes and antennae and nonjumping hind legs, but powerful burrowing adaptations. Some small crickets are dorsoventrally fl attened and wingless and are myrmecophilous.

Reproduction Sperm are transferred mostly in spermatophores. In the Ensifera,

the spermatophore is transferred at copulation, and the vesicle usually

remains attached externally to the vulva; it is eaten by the female and serves an important nutrient function in the development of the fer-tilized embryos. In the Acridoidea, several small spermatophores may be inserted into the female tract, or the tubular part of the single spermatophore may penetrate the spermathecal duct while the vesi-cle remains in the phallus. Some other grasshoppers (the Australian endemic Morabinae of the Eumastacidae) produce no spermatophore, and their sperm is delivered directly to the bursa copulatrix, not the spermathecal duct.

Orthoptera eggs are most often laid in soil, but many other media are also used. Many Ensifera insert them singly or in small numbers, into stems, leaves, or roots, or cement them to stems, twigs, or bark. One Australian species coats the exposed egg laid on a twig with soil particles, apparently to protect the egg from the elements and pos-sibly from parasites. Acridoidea lay their eggs in oothecae or pods, in groups of 4 to over 200, in pithy stems, in soft portions of dead tim-ber, at the bases of grass tufts, or in animal dung; a number of spe-cies cement eggs to water plants below the surface. Burrowing forms deposit eggs in special chambers, lay them in the sides of chambers, or place the eggs around roots.

The ovipositor is often highly modifi ed. In the Ensifera, mostly a needlelike spear is inserted into the substrate, usually the soil, wood, leaf sheaths of grasses, or other plant material. Many species lay spe-cially hardened eggs that are glued to twigs or leaves. Many select a thick leaf, and with alternating penetrations of a highly modifi ed, lat-erally compressed ovipositor, insert a disklike egg into the leaf’s edge. In Caelifera, the ovipositor is relatively similar among the wide range of species. It is short and “ pronged, ” and it penetrates the substrate by opening, closing, and extending the abdomen. In the Acridoidea, the abdomen is frequently stretched to twice its normal length during oviposition.

Development In tropical species, the eggs can hatch in 3 – 4 weeks. In temperate

species, the eggs enter a period of diapause and hatch later. In some species, only a portion of the eggs hatch the following year, with the remainder hatching over a period of years. This serves as a “ safety valve, ” ensuring that the species survives in periods of unfavorable weather. Eggs of some common European Tettigoniidae survive up to nine winters until all eggs laid the same summer are hatched.

A hatchling is enclosed in the embryonic cuticle and is called a pronymph or vermiform larva. At hatching, the eggshell is frac-tured by pulsations of an extrusible structure known as the cervical ampulla, which is part of the dorsal membrane of the neck. This work is assisted by the cutting action of a ridge or row of teeth posi-tioned at the front of the head. The ampulla is also involved in the emergence of the pronymph from the egg repository in the soil or plant tissue and in the intermediate molt by which the embryonic cuticle is cast when the insect is freed.

Nymphs differ from adults outwardly mainly in the reduced devel-opment of wings and reproductive organs, the less developed prono-tum, and a reduced number of antennal segments. Nymphs undergo several molts. Their number can vary between species, between males and females, and under different environmental conditions. Between 4 and 14 molts have been reported so far; the highest numbers were observed in overwintering crickets, the lowest in male gomphocerid grasshoppers. The intermediate stages of the developmental process are called instars. Molting occurs between instars and usually takes place at night under the protection of darkness or in early morning, when the relative humidity is favorable for such processes. The wing

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buds and terminal reproductive structures increase with each molt. Antennal segments are added at molting. To tell apart adults of short-winged grasshoppers from nymphs can be done by the wings; grass-hoppers have two pairs of wings: the fi rst pair is the tegmina and the second pair the wings. In immature grasshoppers, the wings are lat-eral, with the costal margin positioned ventral, as in the adult, but in the penultimate instar, they rotate and assume a reversed, dorsal posi-tion in which the costal margin is dorsal and the morphological ven-tral surface is external, with the hind wing overlapping the tegmen.

REVIEW OF TAXA Suborder Ensifera

Crickets and katydids (bush crickets, long-horned grasshoppers, and relatives) comprise the suborder Ensifera. Ensiferans share important characters with members of the other suborder, the caelif-erans, such as the biting – chewing mouthparts, the modifi ed prono-tum, “ leaping ” hind legs, the similarities in wing venation and shape, and the sound-producing capacities (stridulation) of males. Several phylogenies have been proposed. They result in similar higher taxa but differ with regard to the relations between those taxa. A key question is if the complex elytral stridulatory apparatus, which occurs in the Grylloidea, Hagloidea, and Tettigoniioidea but is absent in the other groups, and the corresponding auditory system evolved only once or at least two times independently. While phylogenies including behavioral characters favor the view of independent evolu-tion of the stridulatory apparatus in Grylloidea and Tettigoniioidea (Gwynne, 2001; Desutter-Grandcolas, 2003), recent molecular phy-logeny supports a more traditional view of a single development of the stridulatory apparatus in Ensifera with several losses of it in some groups (Jost and Shaw, 2006). In Grylloidea, loss of stridulation is a common event that even occurred within genera.

More than 12,000 species are known in about 2000 genera with six superfamilies: Hagloidea, Stenopelmatoidea (Gryllacridoidea), Rhaphidophoroidea, Schizodactyloidea, Tettigoniioidea, and Grylloidea. The classifi cation we follow is illustrated in Fig. 1A .

HAGLOIDEA It contains one family, the Haglidae (Prophalan-gopsidae of some authors), which are known as the ambidextrous crickets or hump-winged crickets. The single living family is divided into two subfamilies. One subfamily, the Prophalangopsinae, consists of three genera, each with a single species, Prophalangopsis from northern India and Tarragoilus and Aboilomimus from Sichuan, China; the Chinese species were discovered as late as 2001. The wings resemble a mixture of a tettigoniid and a gryllacridid. Two genera have the fi rst and second tarsal segments partly fused: a char-acter intermediate between Tettigonioidea that have four tarsal seg-ments and Grylloidea that have three. The second subfamily, the Cyrtophyllitinae, is represented by two living genera. All species are ground dwelling and live in coniferous forests, where they ascend tree boles after dark to broadcast their loud stridulations.

STENOPELMATOIDEA (GRYLLACRIDOIDEA, IN PART) The Stenopelmatoidea has been known as raspy crickets, leaf-roll-ing crickets, wood crickets, Jerusalem and sand crickets, king crick-ets, cave and camel crickets, and other names, it forms a distinctive, conspicuous group with many species quite large and presenting a ferocious appearance. Most, if not all, are nocturnal, with all need-ing to seek shelter during daylight because of the threat of desicca-tion due to the thin integument. When the Grylloptera is recognized as a distinct order, this taxon with the Tettigoniidea constitutes the suborder Tettigonioidea. Because of their nocturnal and subterranean

habits, most species are light colored, with brown or grays dominat-ing the color scheme. Cave-dwelling species are often pale or white: green forms are very rare.

These species occupy most habitats, including the driest deserts and the wettest rain forests. The majority of species seem to be con-centrated in the Old World, especially in the Southern Hemisphere. A few are considered to be minor crop pests, many attract public atten-tion because of their size, and several are considered to be endangered by reason of habitat deprivation or loss due to introduced organisms like rats. The group comprises about 1000 species, but there are many undescribed species known from many parts of the world, especially Australia.

Gryllacrididae Gryllacridids are known by a variety of names. They are best known as raspy or leaf-rolling crickets, but some are called king crickets or tree crickets. Most instars and adults spin threadlike “ silk ” from the mouthparts and use this material in rein-forcing burrows and tying leaves and detritus together to form shel-ters. The integument of the body is soft and pliable ( Fig. 1B ), and the legs are adorned with many spines, some on the hind legs being modifi ed for digging. They range in size from about 5 to 75 mm in body length. This family is best represented in the Old World. Ninety genera with nearly 700 species are known.

Of the few species of gryllacridids that have been studied, all have been found to have peculiar life histories. The majority of these stud-ies come from Australia, where the insects comprise a notable portion of the orthopteran fauna at a given locality. Species may construct bur-rows or tie leaves and detritus together, forming individual enclosures in which they reside during the day. Others live in hollow branches or twigs, and yet others assume a commensal lifestyle with termites.

Raspy crickets feed on a wide range of material. Some are spe-cifi c seed eaters, others predaceous, and others specialize on fl owers or fruits. This last-mentioned activity can be of economic concern when ripe fruit is chewed and when cut fl owers or orchids are dam-aged by feeding activities. At times when gryllacridids inadvertently enter houses, curtains and draperies may be ruined by their chew-ing and clipping as bits of material are tied together with silk to make shelters.

Raspy crickets produce sounds in more than one way. All species possess a femoroabdominal stridulatory mechanism featuring a hind femur that is rough on the inside, with a pattern or shagreening of dorsal surface. This roughened area is rubbed against a pattern of pegs or modifi ed hairs on the side of one or more abdominal tergites. These stridulatory mechanisms seem to show species-specifi c patterns and have been used to distinguish species. Vibrational sounds are pro-duced, often by both sexes, during courtship activities. Depending on the species, sounds are generated by rhythmic drumming of the abdomen on the substrate or by “ stomping ” of the hind feet against the substrate. Some species use combinations of drumming, stomp-ing, and rasping during courtship. The fast-paced drumming is quite audible to the human ear for a short distance. Surprisingly, none of these insects possess any obvious organs that would enable them to hear the sounds they produce. Perhaps, they detect the vibrations through sensory hairs on the pads of the tarsi.

Cooloolidae The odd genus Cooloola with four species from Australia and a variety of peculiar genera from western North America have been placed in this category.

Anostostomatidae (Stenopelmatidae, in Part of Authors) The Anostostomatidae with 41 genera and over 200 species is a relatively recently proposed taxon accommodating a large range of genera

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formerly included in the Stenopelmatidae that live mainly in the trop-ical areas of the earth. Included here are the giant king crickets of Australia, New Zealand, and Southern Africa.

This family includes the Parktown prawn, Libanasidus vittatus , which lives in the Johannesburg area, where it is very well known. Females measure in excess of 6 cm, and most people fear them. They enter houses and beds of sleeping residents at night, and their scut-tling and kicking is a common cause of concern. Their vile-smellingfeces, exuded when disturbed, contribute to the unpleasantness. Myths have arisen regarding this species: some people feel it is an alien invader or the result of a freak mutation. The notoriety of this cricket has been a useful vehicle for educating the public about the biodiversity crisis. One of the most interesting features of this cricket is the tusklike mandibles of males. In this respect, they are similar to those of the New Zealand weta. The mandibles of L. vittatus serve in digging burrows as well as in battles with other males.

The New Zealand tree wetas of the Deinacridinae are often large (8 cm or more in length), secretive, and aggressive species. The biol-ogy of Hemideina spp. is very well known. Some live in tree holes in galleries initially made by beetles or moth larvae. Others live in natural crevices and cavities. They prefer living trees to dead wood. These insects are herbivorous, feeding on leaves, fl owers, and fruit. They may scavenge recently killed invertebrates. They remain arboreal except for a short period when females descend to the ground to oviposit. Some species have a unique-size polymor-phism related to social behavior. There is allometric growth of the head and jaws, much as the Australian king crickets. Certain males have extra instars to gain the larger head and mandibles. There is a dominance hierarchy, with the largest megacephalic males com-manding the most desirable resources, which include galleries and mature females. Smaller males spend more time defending their gal-leries. These males live in galleries with smaller apertures and have been advantaged in dealing with alien predators such as rats. Tree wetas are smooth and shiny, with contrasting bands on the abdomen. Other New Zealand wetas live on the ground. Several species raise their hind legs vertical to the substrate when alarmed. With a female weighing 50 g and measuring 7.5 cm in body length, this is one of the more formidable insects in defense.

All members of the Anostostomatidae are vulnerable to alien predators. The large size of the adults of many species may be effec-tive in battles with rats, for example, but other stages from eggs to moderate-sized nymphs are extremely vulnerable. As a result, several species are threatened with extinction.

Stenopelmatidae Four subfamilies are currently included in this family, but their relationship is not fully resolved. Well known are the Stenopelmatinae, comprising the Jerusalem crickets. The largest genus, Stenopelmatus , occurs in North and Central America. These insects are often known locally as “ potato bugs ” because they have been dug up in garden or potato fi elds. The derivation of the common name of the group, Jerusalem crickets, is shrouded in mys-tery. These insects have behavior patterns similar to those described for several anostostomatids.

There may be 100 species of the genus Stenopelmatus , but only 28 have been described. They are all very similar in overall appear-ance and differ only in their sexual drumming activities. Sympatric species have different drumming patterns. Both sexes and nymphs can produce rhythmic sounds by drumming their abdomens against the sides of their burrows or on the surface of the ground. Some of the sounds are audible from a distance of 20 m. Surprisingly, the nymphs produce species-specifi c drumming patterns in their later

instars. The production of these sounds may serve to keep the spe-cies together and may be effective in areas where there are sympat-ric species.

Copulation is distinctive in this group. In at least one species, the male rolls on his side and, if receptive, so does the female. Mating will not occur unless both partners “ roll. ” Then, facing in oppo-site directions, the male grabs one of the hind tibiae of the female, not damaging her, positions his hind tarsi near her coxae, and curls his abdomen between his and her hind legs toward her subgenital plate. After several minutes, the male’s telescoping abdomen nears the female’s subgenital plate, and he grasps her with his hooks. With this anchor, he everts the phallic lobes and attaches a spermatophore with a larger spermatophylax. In many ensiferans, the spermatophy-lax is eaten, providing a source of nutrition for the mother and her eggs; the Jerusalem cricket female, however, does not consume the organ. Sometimes, though, the female consumes the male after mat-ing; males offer no resistance to cannibalistic females.

TETTIGONIIOIDEA This is the largest superfamily, with more than 6500 species. Katydids (bush crickets or long-horned grasshoppers) can be of economic concern at times. Some fl ying spe-cies can swarm in the manner of locusts. With the “ proper ” environ-mental conditions, even fl ightless species can build in numbers that can affect crops and cause serious losses. The most notable example in the latter category is the Mormon cricket ( Anabrus simplex ) of western North America. It damages a variety of crops and rangeland plants. In Australia, Asia, and Africa, meadow katydids of the genus Conocephalus can build in numbers and move in large swarms. On a local level, many species cause damage to rice and crops from time to time.

On the other hand, the same species are often predaceous, feed-ing on eggs and larvae of other more important crop pests. In tropi-cal regions, rice is attacked by the copiphorine Euconocephalus sp. Phaneropterines seem to provide the majority of species that dam-age crops. Scudderia spp. in North America and Caedicia spp. in Australia both feed on the developing fruits and new leaves of citrus varieties. Phaneroptera species feed on a wide range of crops as well as citrus and coffee, kapok, and mimosas. Another phaneropterine Holochlora pygmaea feeds only on tea. Ducetia species feed on rice on two continents. Elimaea chloris feeds on a range of economic plants, the most notable of which are soybean, sugarcane, tobacco, and tea. The pseudophylline Chloracris prasina damages cacao, dadap, and rubber by its ovipositional habits. The widespread tropi-cal mecopodine Mecopoda elongata feeds on beans, betel, cassava, castor, dadap, maize, potato, rice, sorghum, and tobacco. There are abundant literature references to “ sexavae ” or coconut treehoppers of two genera, Sexava and Segestidia . They are major pests of coco-nut and oil palm. They also feed on banana, karuka, manila hemp, and sago palm. With agriculture ever expanding to more remote areas, additional species not usually associated with economic dam-age can be expected to cause economic problems.

Katydids are widely distributed throughout the world, but the majority of species can be expected in tropical regions, especially the New World tropics. Many species are arboreal or bush dwell-ing. Some live in reeds or grasses, and many live on the ground. A few species can be found in alpine regions far above treeline. Most species exhibit cryptic behavior, especially during the daytime when they are inactive. Other species are aposematic and display warning colors. These species are primarily diurnal in their habits. Immature stages (nymphs) of some species mimic wasps, ants, beetles, bugs, and spiders. Ancestors of katydids probably were predaceous, but

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this role is minor among the extant forms. The majority feed on foli-age, fl owers, and seeds or are omnivorous.

Tettigoniidae Many subfamilies are recognized, with several hav-ing been escalated to family rank as a result of recent investigations. Following the pattern adopted at the beginning of this article, these controversial changes are not recognized here.

The Bradyporinae contain 17 genera with over 160 species found from the Mediterranean area to Central Asia. It now contains the Ephippigerini with nine genera in the Mediterranean, which was for-merly regarded a separate subfamily. The Hetrodinae contribute 14 genera (74 species) in Africa that often occur in aggregations. In some species, both sexes can stridulate. They are characterized by a spiny appearance. The Acridoxeninae, or dead-leaf katydids, are remarkable insects. The group is represented by a single genus with two species in equatorial West Africa, where they are apparently found on spiny plants.

The Phaneropterinae, or leaf katydids, bush katydids, or lyre bush crickets, are the largest assemblage of genera (340) in the fam-ily. It has been accorded family status by some investigators. About 2200 species are known, distributed throughout the world, but the majority of species live in tropical climes. Many species are involved in mimicry complexes. Most nymphs resemble foliage or plant parts, but many are mimics of ants, bugs, spiders, or cicindelid ground beetles.

The Pseudophyllinae, true katydids or bark crickets, include giant, fully winged, leafl ike species (with wings spanning more than 20 cm) and smaller, micropterous ones. Most species are splendid exam-ples of twig, foliage, and bark mimicry. Some species that resemble leaves, transparent holes, and irregular, “ bitten ” pieces, and even colors resembling fungus or lichens, are not uncommon in this group. Over 1000 species are known in 250 genera, with the majority in the New World tropics. The species that provided the name “ katydid ” is a member of this subfamily. All known species are phytophagous, and all known species use the often large falcate ovipositor to deposit eggs in plant tissue – – in bark, twigs, or dead wood. Some species have unusual lifestyles. A Mexican species of Pterophylla has been observed cross-ing a stream underwater. One species of the southeast Asian genus Callimenellus occurs in marine littoral rock crevices; others live in leaf litter on the forest fl oor.

The Microtettigoniinae are represented by a single genus, Microtettigonia from southern Australia. These are minute (males as small as 5 mm) micropterous diurnal katydids that are extraordinarily fast moving. They live in grasses and lilies, and they seem to feed on fl oral parts.

The Conocephalinae is a large cosmopolitan group that com-prises at least four tribes with more than 1000 species in 172 gen-era. The Gondwanan-distributed Coniungopterini is represented by three genera: two occur in Australia and New Guinea, and a third is found in Chile. The genus Conocephalus is represented by more than 50 species in Australia alone; worldwide there are over 170 spe-cies. They are small, agile katydids with a relatively broad, blunt fas-tigium. They are similar in appearance and habit and often occur in large numbers. Some species are diurnal, others nocturnal, and still others are active both day and night. Conocephalus species can be of economic concern at times. At least one species has been distributed through commerce.

Other genera have a much smaller number of species and are widely distributed. The Copiphorini are often associated with grasses, where their slender, bladelike appearance renders them almost invis-ible as they perch on the stems. The species associated with grasses

and reeds feed largely on the fl oral parts of the host plants, preferring seeds. The mandibles are unusually strong, and this is an adaptation for seed predation. The buzzing calls are familiar sounds to most resi-dents and visitors to appropriate habitats on all continents, but few people have ever seen the producers of the sounds they frequently hear because of the insects ’ secretive and cryptic habits. Thus, many attribute their sounds to cicadas. The other subfamily, the Agraeciini, is a disparate assemblage that most likely comprises a number of higher taxa. Members of this group have an extraordinary size range, with some of the world’s most robust species represented.

The Mecopodinae (56 genera, 151 species) or Kutsuwa bush crick-ets are usually large (some species have wingspans � 20 cm), and most species are fully winged and resemble either dead or living leaves to a remarkable degree. Others are short winged or wingless in at least one sex. Females sometimes stridulate. Most species are confi ned to the Old World. The subfamily is represented by two tribes, the Mecopodini and Moristini (Sexavini). Members of three genera are called coconut treehoppers because of the damage they cause to coco-nuts. Some species of this subfamily are kept in cages in Asia for the songs they produce.

The Phyllophorinae, or giant leaf katydids, are among the larg-est of all tettigoniids, with wingspans greater than 25 cm. Some 10 genera and over 60 species are known, mostly from the rain forests of Indo-Malaysia, New Guinea, and northern Australia. They are related to the mecopodines and the phaneropterines.

The Phasmodinae, or stick katydids, are wholly confi ned to south-western Australia. They occur in winter and spring and are largely gone as the hot days of summer approach. They are very elongate and wingless in both sexes. They can cause economic concern when they feed on wildfl owers in plantings in parks adjacent to natural areas. The remarkable resemblance to Phasmatodea is one of the most striking examples of convergence in the orthopteroid insects.

The Zaprochilinae, or pollen- and nectar-feeding katydids, are represented by four genera comprising 18 species from Australia. They are usually gray, setose, soft-bodied insects, and some species are fully winged, with the tegmina held at an angle and rolled; some species are micropterous in males and wingless in females. The Kawanaphila species have been important study organisms in stud-ies of sexual selection.

The Tettigoniinae, in nearly 150 genera with over 850 species, comprising shield-backed katydids, wart-biters, or great green grass-hoppers, is one of the largest and most widespread of tettigoniid subfamilies, with the majority of representatives in temperate climes of both hemispheres. The common name, shield-backed katydids, is derived from the development of the pronotum, which is often extreme. While most are predaceous or specialized feeders, the Mormon cricket ( Anabrus simplex ), the Coulee cricket ( Peranabrus scabricollis ) of North America, and Decticoides brevipennis of Africa can occur in large numbers during favorable years, causing enor-mous damage to crops. The wart-biter ( Decticus verrucivorus ) was used during the Middle Ages to “ cure ” warts by allowing the aggres-sive insects to bite them off. Perhaps a substance in the insect’s saliva contributed to the cure. The subfamily is diverse in form, rang-ing from among the smallest of tettigoniids to some of the largest. Fully winged and micropterous ( Fig. 1E ) species are known. The Onconotini are unusual micropterous katydids living in shrubbery.

The Saginae is a small but characteristic subfamily of voracious predators or large insects. Four genera are represented, all from the Old World. Saga species can enter a cataleptic state characterized by complete immobility lasting some 20 min followed by a slow recov-ery. The function of this behavior is unknown.

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The Austrosaginae comprises fi ve genera, some of which use the powerful mandibles to crack seeds and feed on fruits. Listroscelidinae is a disparate assemblage of genera, many of which will probably be moved to other subfamilies when the group is fully revised. All species appear to be predaceous, some nocturnal and others diurnal. Some of the world’s most spectacular katydids are members of this subfamily. Many are capable of delivering a painful bite when handled. The center of distribution for this group seems to be Australia.

The Meconematinae (80 genera, over 500 species), or oak crickets or swayers, are small, delicate, greenish-yellow katydids; their distri-bution is tropical or subtropical. The notable exception is Meconema thalassinum , which occurs in Europe and Asia and has been intro-duced into the eastern United States. This species has lost the tegmi-nal stridulatory apparatus but produces sound by drumming with a hind leg on the substrate. The meconematines have been confused with the Phisidini of the Listroscelidinae, which, although somewhat similar in appearance, have an entirely different lifestyle. The phisi-dine species are nocturnal predators and have typical listroscelidine eggs. Eggs of meconematines are incredibly large for the size of the katydid and can be seen through the thin integument of the female. They are laid in decaying wood or other plant tissue, such as galls made by wasps, with the fl attened, hard cap protruding from the substrate. The Tympanophorinae, or timbrel bush crickets, comprise a single genus confi ned to temperate Australia. The tegmina are unique in that some species bear four kinds of stridulatory teeth on an expanded “ rib. ” There is evidence that soft structures on the rib may provide openings for a lubricant or a substance released from a chamber or reservoir beneath it. This feature is probably associ-ated with the unusual reproductive biology of species. In other tet-tigoniids, females are drawn to stridulating males, or answer them with their own calls, and the pairs are eventually brought together. The situation must be different in the tympanophorines, since the females are fl ightless and incapable of producing sounds. Male strid-ulatory behavior is unusual: they sing from perches for a short time and then fl y 30 m or more to another perch and continue their song. How a fl ightless female can attract the attention of the transient male is unknown. All tympanophorine species are nocturnal and preda-ceous. They use the short forelegs to capture small-insect prey. The Lipotactinae contain only two genera with 30 species living in forests of southeast Asia; fossils are also known from the Amber in Europe. They have small bodies with large eyes on the top of an unusual heart-shaped head. Few observations have been made that record the katydids catching their small prey on the “ jump ” , in midair.

RHAPHIDOPHOROIDEA It has the single family Rhaphido-phoridae. Camel, cave, and sand-treader crickets are fairly similar in appearance ( Fig. 1C ). An extinct subfamily is known from amber inclusions. All members are apterous, but some can produce sounds by rubbing the inner faces of the hind femora against the opposing side of the abdomen and by rhythmic drumming of the abdomen against a substrate, be it the ground, a twig, or a branch. All have a humpbacked body structure with very long hind legs and anten-nae. Some of the sand-dwelling species have the hind legs modifi ed into “ sand baskets ” for digging. Some groups are wholly confi ned to caves and others are obligate burrowers; the majority, however, live in leaf litter or dark crevices, where they spend the daylight hours and emerge only on humid nights to feed on detritus and leaf lit-ter. Some feed on fungi, and there is at least one record of a cave-dwelling species that feeds on newly hatched birds. One camel cricket is cosmopolitan in its distribution, being moved in commerce, and is

said to be a pest of greenhouses. About 550 species in 80 genera are known, with most species coming from the Indo-Australian area and Polynesia.

SCHIZODACTYLOIDEA It has the single family Schizodac-tylidae. The splay-footed crickets are among the most bizarre of orthop-teroids ( Fig. 1D ). There are fully winged as well as apterous species. They are broadly expanded by the possession of lobelike or digitiform processes, which enable the crickets to run across dry sandy surfaces with effi ciency. One interesting feature of the group is that members that have been studied have lower chromosome numbers than most typ-ical orthopteroids. The splay-footed crickets are primarily predaceous, but one is considered to be a minor crop pest. Two genera together with 15 species are known. They occur in parts of India, Myanmar, southwest Asia ( Schizodactylus ), and South Africa ( Comicus ).

GRYLLOIDEA It includes the true crickets and mole crickets that range in size from less than 1 mm to more than 6 cm. Most spe-cies possess “ ground colors, ” and few green forms are known. This is an adaptation to living on or in the ground.

The Grylloidea can be divided into a few very unequal families. Nearly 600 genera are known, encompassing over 4000 species, that comprise the Gryllidae; only about seven genera and almost 100 spe-cies comprise the Gryllotalpidae . Although the majority of species are tropical, large numbers occur in all the temperate parts of the world. All terrestrial habitats seem to be inhabited, except the high-est mountain peaks. A few species can “ skate ” on water surfaces, and several live in mangrove swamps, where they use the stems to sub-merge themselves in saltwater when danger threatens. Many species burrow deep into the ground and seldom emerge. Others are blind, lack pigmentation, and live deep in subterranean caves. A number of species are commensal, living with rodents, ants, termites, and even mankind. Eggs are laid singly and deposited in the ground or in plant tissue such as decaying wood or grass stems.

Many crickets are crop pests, and population explosions sporadi-cally occur with devastating results. Invasions of human habitations by crickets cause angst owing to the interminable chirping. Crickets around the world have been known to ravage foods and furnishings.

The arrangement of crickets into higher units changed several times in recent history. A broader, more classical view is adopted here.

Gryllidae The true crickets comprise the principal family of the superfamily. Body size can range from less than 5 mm to more than 50 mm. The family is currently divided into 26 subfamilies, and vari-ous classifi cations elevate some of these taxa to family level. Only some subfamilies can be highlighted shortly. The Gryllinae contain the crickets known to almost everyone. There are more than 1000 species in over 100 genera known from all parts of the world. Field crickets and house crickets belong to this group. Almost all species live on the ground, and some construct elaborate burrows that are often modifi ed to amplify sound production. The house cricket, Acheta domesticus , can be considered to be a domesticated insect. It is used in commerce as a food for mammals, birds, and reptiles and seems unable to exist for any length of time in nature.

Several cricket species are kept, mostly in Asian countries, for the songs they produce. They are the source of a rich folklore and are regaled in poetry and song. Fighting crickets are an important part of the social scene in many Asian countries. The short-tailed crick-ets, a group that is quite prominent in Asian culture, are notable for the extensive galleries they make. There are brood chambers where

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the young are looked after. Several species cause damage to crops by feeding or destroying the roots of the plants.

The Nemobiinae, or pygmy or dwarf crickets, comprise nearly 300 species in more than 50 genera and, as the name suggests, are small. While most forms are winged, there are many apterous species only a few millimeters in body length ( Fig. 1G ) that can easily be mistaken for nymphs of other species. Several genera exist in marine habitats. A number of genera in several parts of the world are adapted for life deep in caves and lava tubes. The majority of species live on the ground, often in moist habitats. Their numbers can be incredible in certain situations. Both diurnal and nocturnal species are known.

The Trigonidiinae, or leaf-running or sword-tailed crickets, are small, ground-dwelling or bush-dwelling crickets that are usually diurnal. They are active and often brightly colored. Some have a metallic sheen. Many species mimic spiders, ants, or wasps to mask their edibility. Eggs are deposited in stems and bark. More than 500 species are known in 36 genera. Many genera are cosmopolitan or at least occur on more than one continent. Preferred habitats are in rank vegetation, including shrubs, grasses, and small trees, but sev-eral genera occur in leaf litter. One genus with long tibial spurs can skate over water.

The Eneopterinae and Podoscirtinae, or bush crickets, are small- to medium-sized slender crickets. These crickets usually live in shrubs, trees, herbaceous vegetation, or grasses. A small number can be found in leaf litter. There is a range of color in this group depend-ing on the habitats occupied. Over 100 genera with more than 600 species are known. Most examples are from the tropics. Virtually none are of economic signifi cance.

The Phalangopsinae, or spider crickets, are long-legged, rather fl imsy crickets that are often gregarious in habit. This and some closely related subfamilies together comprise 130 genera and over 600 species, with the majority in the Old World tropics. Some species occur on the ground or in tree holes or decaying logs. Large num-bers live in caves, crevices, or in the cavities created by large animals. Similar habitats afforded by dams, bridges, and buildings attract these crickets. True cave crickets belong to this subfamily. The cheerful songs of oriental species are prized, and these crickets are often kept in cages for such reasons.

The Sclerogryllinae, or stiff-winged crickets, are represented by only two genera and few species. These crickets occur in Africa and southern and eastern Asia, where they live in leaf litter. The Pteroplistinae, or feather-winged crickets, are represented by 10 gen-era and 23 species. The Cachoplistinae are sometimes called beetle crickets because members of at least one species strongly resemble small beetles.

The Oecanthinae (9 genera, 162 species), or tree crickets, have a worldwide distribution, but only nine genera and many species are known. Their nocturnal calls are well known to many people, although the insects themselves are seldom seen by humans. Some males uti-lize holes in leaves to amplify and direct their songs. They are also kept in cages in Asian countries because of the melodious songs they pro-duce. Tree crickets are both benefi cial and important local crop pests. Nymphs are often predaceous, feeding on a variety of insects, includ-ing aphids and scales. At times, females oviposit in developing fruits and have been involved in transmitting plant diseases. Tree crickets have a characteristic appearance ( Fig. 1H ) and are usually pale green-ish white, ranging from 1.0 to 1.5 cm in length.

The Mogoplistinae, or scale crickets, are a widespread and often common assemblage of small, fl attened species, all of which are covered with minute scales. About 30 genera are known, compris-ing over 300 species. The majority of species live in the Old World

tropics. Many species live on the leaf surfaces, and there is an abun-dance of species that live in leaf litter. A single European species is considered to be intertidal. One tribe is known to be associated with rodent burrows. Both nocturnal and diurnal species are known. They are mostly small, ranging from 1.0 to 20 mm. The beautiful tones and sequences of the male song are valued in the Orient, and sev-eral species are kept in cages and sold in market for their songs. The Myrmecophilinae, or ant crickets, are minute, scale-covered, wingless crickets. There are six genera in this small subfamily, with more than 70 species found throughout the world, although most are known from tropical and subtropical regions. They are associated with ants, often living in the nests with them or following them along their trails. Some species have a wide range of hosts; others are known from only one species. Their commensal relations are unclear, but they seem to be unable to live independently for any period of time. A few species exist with termites. Some species seem to be parthenogenetic. Eggs are relatively large for the size of the female producing them. They are robust crickets that live in association with ants.

Gryllotalpidae The mole crickets comprise seven genera with about 100 species worldwide. Most species are found in the cosmo-politan genus Gryllotalpa . Mole crickets use the extraordinarily devel-oped forelegs for digging deep, permanent galleries and foraging for plant roots. Some mole crickets are known to collect seeds and store them in larders in circular chambers underground for future use. Some species brood eggs in chambers, and in many species, both sexes stridulate. The calling songs are often of short duration and very loud. The horn-shaped entrance chamber of the burrow is used dif-ferently by different species to increase the male’s acoustical output. Most species are herbivorous, but a few are carnivorous. Several cause major damage to crops by feeding on roots, on seedlings, or both.

Suborder Caelifera The short-horned grasshoppers and locusts and their relatives

comprise the large and well-known suborder Caelifera. Rarely, this group is treated as a separate order.

Most caeliferans are diurnal, but increasingly investigators are discovering that many species are active both day and night. Males of many species stridulate in bright sunshine; rarely, those of others sing on warm nights. Although primarily tropical, many species occur in all parts of the world. Some are semiaquatic, and only a few are true burrowers. Almost all species feed on plant material, but many feed on dead members of their own or other species. None are com-mensal. Aposematic coloration is a feature among many species.

Copulation in the Caelifera is rather uniform, with the male clinging to the back of the female for a considerable period of time with the spermatophore elongated and occupying the female’s geni-tal tract. There is no visible external spermatophylax. Eggs are laid in pods or oothecae that are enclosed in a reticulate membrane and covered by a foamy secretion that dries out eventually. Eggs of most species are deposited directly into the ground, but others lay eggs in plant tissue or in cracks in bark.

Many species are disposed to gregarious behavior and swarm-ing, with locusts offering the best example of this behavior. All true locusts are placed in the Caelifera. However, many other species not properly designated as locusts can become extraordinarily numer-ous and cause great damage to crops and other vegetation. Many species are eaten in Asia and Africa, usually fried. Many others are dangerously poisonous, and deaths have been recorded from eating these insects in Africa. After fi res, the predominant colors among

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nymphs are dark, often black. This characteristic, called fi re melan-ism, is found in almost all grasshoppers in all areas. The time span for these changes is extremely short. However, some surviving adults that become very dark after a fi re produce nymphs that show little or no melanism.

The more than 2400 genera and 11,000 species comprising the Caelifera are arranged in superfamilies, suborders, or infraorders depending on the classifi cation followed. Here they are regarded as superfamilies and are as follows ( Fig. 1 ): Acridoidea, Eumastacoidea, Pyrgomorphoidea, Tanaoceroidea, Pneumoroidea, Trigonopterygoidea, Tetrigoidea, and Tridactyloidea.

ACRIDOIDEA ( SENSU LATO ) This includes the grasshop-pers and locusts, which comprise the largest superfamily of the sub-order Caelifera. More than 8000 species in nearly 1700 genera are known worldwide. Adults range in size from less than 1 cm to more than 25 cm.

Many grasshoppers have a disparity in size between males and females, with the former being much smaller than the latter. In many species, males ride “ piggyback ” on females, not always copulating but “ protecting ” their prize and defending their potential progeny from other males with similar intent.

Grasshoppers have a short, almost invisible ovipositor. The eggs are laid in a pod covered by a protective coating. Many species ovi-posit on grasses, wood, and other plant tissue. A North American species has been observed ovipositing in dry buffalo dung. A number of species, especially locusts, utilize “ lekking sites ” to oviposit. Large numbers of females lay eggs in the same place year after year. Knowledge of such behavior can be valuable in planning the control of pest species. Many grasshoppers take advantage of walking tracks or nonpaved roads for such activity. In oviposition, the female uses muscular contractions to extend the abdomen into the ground, often telescoping many times its length. The digging process is also per-formed by contractions and is aided by the teeth at the end of the abdomen. Upon hatching, the vermiform larva wriggles to the sur-face of the soil and upon reaching the surface, molts into the mini-ature form that will eventually become the adult. Nymphs undergo a series of approximately four to six molts, each one resembling more and more the adult in color pattern and shape. Gregarious grasshop-pers illustrate synchronized molting, with all nymphs shedding their skins within hours of one another.

Locusts are species that occasionally form dense migratory swarms. These are often so large that they cross oceans but most occur in inland regions. Worldwide, more than 20 species from several sub-families of Acrididae form migratory locust swarms.

The number of families depends on the classifi cation followed. The scheme followed here ( Fig. 1A ) refl ects the latest molecular attempts to establish a phylogenetically based classifi cation based on defensible evidence.

Pamphagidae The Pamphagidae comprises generally larger, sluggish grasshoppers often resembling stones and bark. They have an array of body shapes ( Fig. 1I ). The family has an Old World dis-tribution, with the majority of species occurring in Africa and a few in Europe and Asia. It is absent from Australasia. Several species are known in which unmated females produce sounds, not the males as in other families. This is done by fl apping the forewings that are reduced to hardened scales against the body.

Lentulidae The lentulid grasshoppers have been called “ nymph-like ” grasshoppers and range in size from 8 to 25 mm in body length. These ( Fig. 2A ) grasshoppers are wingless. They occur in southern,

eastern, and central Africa. Most species live in bushes, and at least one species causes feeding damage to nursery stock. One species prevents a weedy shrub from becoming a pest.

Tristiridae The Tristiridae, or Andean wingless grasshoppers, are small to moderate in size. The body shape is variable, but the integument is always wrinkled and the color is brown or grayish. The family has three subfamilies found only in the mountains of Cordilleran and Patagonian South America. They are found at high altitudes (2800 – 3000 m). Their protective coloration renders them almost invisible on pebbles and gravel, but aside from that nothing is known of their biology.

Ommexechidae The Ommexechidae are called South American toad-hoppers. The family includes 13 genera with some 30 species, all from South America. They live on the ground, inhabiting “ coarse ”

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FIGURE 2 (A) A lentulid grasshopper, Lentula callani , from Africa. [From Dirsh, V. M. (1975). “ Classifi cation of Acridomorphid Insects. ” Classey, Faringdon, U.K.] (B) Oedipoda miniata , Oedipodinae. [From Dirsh, V. M. (1975). “ Classifi cation of Acridomorphid Insects. ” Classey, Faringdon, U.K.] (C) Flying gooseberry, Bullacris uni-color , male; tegmina and wings absent from females. [From Dirsh, V. M. (1975). “ Classifi cation of Acridomorphid Insects. ” Classey, Faringdon, U.K.] (D) Cota saxosa , a Peruvian species. Note fl anges on legs and pronotum. [From “ Genera Insectorum. ” (1906). Vol. 48.] (E) Bruntridactylus tartarus . Note fan-shaped hind wing. [From Saussure, H. (1874). “ Voyage au Turkestan, Orthopt è res. ” ]

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vegetation in dry, sandy, or stony areas. They are of no economic importance.

Romaleidae The Romaleidae, or lubber grasshoppers, are regarded as a subfamily of the Acrididae in most older works. Recent molecular investigations, however, show that full family status is more appropriate. These grasshoppers are moderately large to very large in size and are often very colorful. The family has nearly 500 species in two subfamilies all found in the Americas. They occur in many habitats from desert to tropical rain forest. Some live on the ground, closely resembling stones or “ toads ” ; others are found in bushes, and still others high in trees. Many species show aposematic coloration – – if not in the adult stage, then as nymphs. Some species can produce a hissing sound when disturbed, and bubbles can be produced from spiracles when the insects are greatly disturbed. In many aspects of both appearance and behavior, these grasshoppers resemble the pyrgomorphs. Few romaleines, however, are associated with grasses or sedges. The lubber grasshopper, Brachystola magna , of the southwestern United States, can be a serious road hazard when killed by automobiles. Their crushed bodies have caused cars to skid and accidents have occurred. The largest of grasshoppers occur in this family. The tropical American genera Titanacris and Tropidacris normally feed on vines, but at times they can become pests of plantations by defoliating plantation trees. They are called “ giant locusts, ” but they are not really locusts at all because they do not form swarms.

Lathiceridae The Lathiceridae have been called desert gravel-hoppers. They are another peculiar small group known only from Africa. There are only three genera and four species, and nothing is known of their biology except that they burrow in sand and spend considerable time underground. They strongly resemble pebbles.

Pamphagodidae The Pamphagodidae (Charilaidae) are called the twin-keeled grasshoppers because of the parallel longitudinal carinae in the surface of the pronotum. There are four genera, com-prising only fi ve species, in this very small group from Africa.

Acrididae The Acrididae, or true locusts or grasshoppers, com-prise the largest family of the suborder, and a full range of most of the features already described can be found here. Species range in size from less than 5 mm to more than 12 cm. The body form refl ects grasshopper’s role in the habitat. Short, stout, stone- or toadlike spe-cies are known, as well as stem- or twiglike grasshoppers. The colors span the complete range for the order, with browns or earth colors predominating.

Grasshoppers occur everywhere that orthopteroids are found. Many of the higher groups have restricted distributions, but the majority of species are tropical. Until recently, around 25 subfamilies were recognized, with more than 1500 genera. The characteristic songs are produced by males to attract females. Since these grasshop-pers are primarily diurnal, color and behavior play important roles in species recognition. Some species have more than a dozen move-ments necessary for mate recognition. Elaborate colors and patterns and modifi cations of body pairs are associated with this behavior. But not all courtship occurs during the day. Some groups mate under the cover of darkness and rely on chemical clues to fi nd mates. With these species, color is mostly protective, and bright colors are associ-ated with aposematic features. Grasshoppers have a worldwide dis-tribution and extend into some of the very cold regions of north and south. In this respect, they occupy more territory than the Ensifera. Only a few subfamilies can be highlighted here.

The Oxyinae include many species associated with water and grasslands. Oxya japonica , one of the most destructive grasshoppers in rice in southeast Asia, does only minimal damage in Australia. Bermiella acuta from Australia occurs on sedges, rushes, and grasses near water and has adaptations for aquatic life such as dense, water-excluding patches of hairs on the distal abdominal sterna and tegmina, and an “ air chamber ” formed by the doming of the costal area of the tegmen over the fi rst abdominal spiracle.

The Gomphocerinae are an important component of the acridid grasshoppers. The songs of stridulating males are a summertime characteristic in the meadows of the Northern Hemisphere. Several species of the same genus may occupy similar habitats and have simi-lar feeding habits. The calling songs of the respective species are dif-ferent and serve as isolating mechanisms. Females are attracted only to the males that perform the calls of their own species.

The Catantopinae, or spur-throated grasshoppers, comprise many species (84% of the fauna in Australia). Some are very colorful. Many catantopines produce no audible sound, but some perform drumming actions on their host plants with the hind legs, thereby announcing the presence of a mate without the need of acoustical amplifi cation. The responding members of the opposite sex merely move to the point of the drummer to consummate the union. A few other spe-cies produce a soft sound by rubbing the mandibles together. This can serve two functions. Some do this only when grasped, a startling reaction that might cause a would-be predator to drop the grasshop-per. Others produce a similar sound from perches in shrubbery, obvi-ously as an attractant to potential mates.

The Cyrtacanthacridinae, or large spur-throated grasshoppers, comprise some of the world’s most important locust pests. Valanga irregularis from Australasia is one of the world’s largest grasshop-pers. It feeds on the leaves of trees and shrubs and can cause dam-age to fruit, nut, and plantation trees. Grasshoppers and locusts of the genus Schistocerca are members of this subfamily.

The Acridinae and the Oedipodinae are large groups ( Fig. 2B ) with a worldwide distribution. Many Oedipodinae have brightly colored hind wings, while some Acridinae have prolonged bodies with long, slanted heads. These groups contain some of the most phylogenetically advanced grasshoppers. Several locusts are included in the Oedipodinae, such as Australia’s most important locusts pest, Chortoicetes terminifera , or the plague locust Locusta migratoria .

The Pauliniinae, or aquatic grasshoppers, contain a single, small- to medium-sized species with a smooth body integument. Some authors regard it a separate family. It is only known from South America. Although other grasshoppers are aquatic, these grasshop-pers are more wholly aquatic than any others. They can skate on the surface or dive and swim beneath it. Eggs are laid on the submerged parts of water plants. Their terrestrial behavior seems to be mostly nocturnal. They feed on aquatic plants, and one species, Paulinia acu-minata , has been introduced into Africa for the control of Salvinia .

TANAOCEROIDEA This includes a single family, the Tanaoceridae. Once considered to be related to both the eumastacids and xyronotids, the family Tanaoceridae comprises two genera with a few species from the deserts of western North America and Mexico. Members of Mohavacris have been found on sagebrush ( Artemisia tridentata ), where they closely resemble the bark of the thick stems. Tanaocerus species occur on the ground or on shrubbery. Both gen-era are nocturnal and are active on the cold nights of winter. Eggs are apparently laid in the ground and hatch in early autumn.

PYRGOMORPHOIDEA This now includes only the Pyrgomor-phidae, comprising a most diverse assemblage of genera. The size and

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shape of the grasshoppers are extremely variable, but the head has a characteristic fastigial furrow. The family comprises some 30 tribes with 150 genera and nearly 500 species; two subfamilies are rec-ognized at the most. The family is mostly tropical, with the greatest number of species being from Africa and Madagascar, but the greatest diversity of genera is from the Australasia. Only few species are known from Mexico and South America.

Pyrgomorphs live on bushes, herbage, grasses, and sedges and on soil and sand. Although many are camoufl aged and show adaptation in body shape with twigs, grasses, leaves, and so on, many are stunning examples of aposematic coloration. They perform impressive displays when annoyed or threatened. Several species eject irritant fl uids or a foamy froth when irritated. Not only are some of these substances toxic to mammals, birds, and reptiles, they are poisonous to humans. The majority of species oviposit in the ground like other grasshoppers, but some have been observed ovipositing in rotting logs, epiphytes and, most likely, the soil in trees caused by the presence of epiphytes. A few species are facultatively aquatic. Many species are gregarious, especially in the juvenile stages, and move together in the manner of locusts. At times they cause damage to crops but, in general, they are not pests.

PNEUMOROIDEA (BLADDER HOPPERS OR FLYING GOOSEBERRIES) This comprises a single, most peculiar family, the Pneumoridae. They are usually large, with some species reaching 10 cm or more in length. The body shape of males is characteristic ( Fig. 2C ), that of females more resembling a normal grasshopper. The major part of the abdomen in males forms a huge, infl ated, resonating chamber that is highly translucent. Females produce sounds but in a different way. Biological observations made more than 200 years ago indicate that males produce a loud noise after dark from shrubs in dry habitats. The sound, with its deep resonance, is often mistaken for that of a larger animal such as a bullfrog. There are two subfamilies with nine genera and some 20 species. They are all confi ned to south-ern and eastern Africa. They are of no economic importance.

EUMASTACOIDEA It consists of two families, the Prosco-piidae and the Eumastacidae. Both have short antennae and an angular head that often appears too large for the body. Most spe-cies are wingless, but there are winged species that often resemble damselfl ies. The proscopiids, or false stick insects, are readily dis-tinguished by elongate and twiglike appearance. They have an exag-gerated head. All species are wingless, and some can be quite large (2.5 – 16.5 cm). Sixteen genera are all confi ned to South America.

The Eumastacidae, or monkey grasshoppers, is a much larger group. Seven subfamilies, regarded as separate families by some authors, have been recognized with more than 1000 species. Most species are small, with the body seldom exceeding 4.5 cm. Many are wingless, but there are many Old World forms that are fully winged and readily fl y. Most species have a characteristic way, shared with the proscopiids, of sitting, exposed, with the hind legs splayed akimbo. They are diurnal and readily fl y in the sun, and they resem-ble damselfl ies in several respects. Eumastacids feed on a variety of plant types ranging from grasses and sedges to desert shrubs and ferns in Old World rain forests. Probably the majority of species are nocturnal.

The Australian endemic subfamily, Morabinae, comprises 42 gen-era with 123 species. They are elongate, matchsticklike plain brown or green grasshoppers that do not sit with legs akimbo. They live on a wide variety of plants and are often very localized in their distribution. A fossil species of the extant genus Erucius , of the Eruciinae, has been

discovered in Oligocene deposits in western North America. Present-day species in this genus are found in Malaysia and the Philippines.

TRIGONOPTERYGOIDEA It comprises two families: Trigono-pterygidae and the Xyronotidae. The Trigonopterygidae have been called broad-leaf bushhoppers ( Fig. 1A ). The group is confi ned to Asia, and several of the species occur in Borneo, where they live on the ground in dead leaves they resemble.

The Xyronotidae, or razor-backed bushhoppers, comprise a single genus with only two species with no known relatives. These grass-hoppers live on the ground in leaf litter and have continuous genera-tions. They are found only in Mexico.

TETRIGOIDEA This contains the grouse locusts or pygmy grasshoppers. These are small, usually gray, black, or mottled grasshop-pers seldom exceeding 20 mm in body length ( Fig. 2D ). Depending on the classifi cation, there are two families, or one family and many sub-families. About 1500 species are known in 255 genera, with the major-ity of species in the Tetriginae. Most species live on the ground, most often on moist ground or along streams and ponds, where they feed on algae and diatoms. Members of the tribe Scelimini are fully aquatic and can swim effectively underwater. In tropical climes, some species are arboreal and live among lichens and mosses in tree buttresses or even higher in the canopy. Eggs of the terrestrial species are laid in the soil and bear a peculiar terminal fi lament that is directed upward when the eggs are laid. They are mostly of little economic concern, although some species are said to feed on rice.

TRIDACTYLOIDEA This is a small group containing some of the most bizarre of the orthopteroids. The pygmy mole crickets, pygmy sand crickets and mud crickets, and sand gropers are peculiar in many respects. They range in size from less than 4 mm to more than 80 mm. Three families are recognized. The Tridactylidae and Rhipipterygidae are more closely related to one another than to the Cylindrachetidae.

Tridactylidae and Rhipipterygidae The tridactylids and rhip-ipterygids are small, usually variegated black, yellowish, or reddish minute cricketlike insects ( Fig. 2E ). The two families comprise about 220 species in 19 genera.

Most of the tridactylids and rhipipterygids are associated with damp habitats. They seem to be gregarious, and those that live in these situations can construct “ nests ” out of mud and debris to spend the night or to “ hibernate. ” Many are active swimmers. There is another group that is arboreal, living on leaf surfaces in tropical climes, where they feed on the rain of particulate matter from the canopy. Many of these species have wasplike color patterns and “ jerky ” movements. Others living in the same habitats are dark blue and have white tips to the antennae.

Cylindrachetidae The Cylindrachetidae, or sand gropers, have an elongate or wormlike appearance. There are nine known species in three genera. They refl ect a Gondwanan distribution, with species in Australia, New Guinea, and Patagonia. Sand gropers build galler-ies in moist soil by compressing the soil with their powerful forelegs, burrowing up to 2 m depth. In some seasons and after rain, they bur-row close to the soil surface producing long, conspicuously raised trails. Nymphal development may extend over several years. Sand gropers consume a wide array of plant, fungal, and arthropod mate-rial. At least one species causes considerable damage to wheat in Western Australia, where large populations build up in the soil and feed on the root of plants.

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See Also the Following Articles Crickets ■ Locusts

Further Reading Bailey , W. J. , and Rentz , D. C. F. (eds.) ( 1990 ) . “ The Tettigoniidae: Biology,

Systematics and Evolution ” Crawford House Press , Bathurst, Australia . B é thoux , O. , and Nel , A. ( 2002 ) . Venation pattern and revision of Orthoptera

sensu nov. and sister groups. Phylogeny of Palaeozoic and Mesozoic Orthoptera sensu nov . Zootaxa 96 , 1 – 88 .

Chapman , R. F. , and Joern , A. (eds.) ( 1990 ) . “ Biology of Grasshoppers ” Wiley , New York .

Desutter-Grandcolas , L. ( 2003 ) . Phylogeny and the evolution of acoustic communication in extant Ensifera (Insecta, Orthoptera) . Zool. Scr. 32 , 525 – 561 .

Dirsh , V. M. ( 1975 ) . “ Classifi cation of Acridomorphid Insects . ” E. W. Classey , Faringdon, U.K.

Field , L. ( 2001 ) . “ The Biology of Wetas, King Crickets and Their Allies . ” CAB International , Wallingford, Oxon, U.K.

Flook , P. K. , Klee , S. , and Rowell , C. H. F. ( 1999 ) . Combined molecular phylogenetic analysis of the Orthoptera (Arthropoda, Insecta) and impli-cations for their higher systematics . Syst. Biol. 48 , 233 – 253 .

Gwynne , D. T. ( 2001 ) . “ Katydids and Bush-Crickets: Reproductive Behavior and Evolution of the Tettigoniidae . ” Cornell University Press , Ithaca, NY .

Jost , M. C. , and Shaw , K. L. ( 2006 ) . Phylogeny of Ensifera (Hexapoda: Orthoptera) using three ribosomal loci, with implications for the evolution of acoustic communication . Molec. Phylogenet. Evol. 38 , 510 – 530 .

Naumann, I. D. (ed.) (1991). The Insects of Australia, a Textbook for Students and Research Workers, Vols. 1, 2. Melbourne University Press, Carlton, Australia.

Preston-Mafham , K. ( 1990 ) . “ Grasshoppers and Mantids of the World . ” Blandford , London .

Rentz , D. C. F. ( 1996 ) . “ Grasshopper Country: The Abundant Orthopteroid Insects of Australia . ” New South Wales University Press , Sydney, Australia .

Ovarioles Diana E. Wheeler

University of Arizona, Tucson, AZ

O varioles are egg-producing tubules that are the fundamental units of ovaries in female insects. The number of ovarioles in each ovary is typically 4 – 8, but varies widely depending

on the particular insect and its ecology.

GENERAL ARRANGEMENT AND STRUCTURE Each ovariole is a tube in which oocytes form at one end and

complete development as they reach the other. The terminal fi la-ment and the germarium, which contains germ cells, are at the dis-tal end. Ovarioles may have one of several topological arrangements within an ovary. In some species ovarioles join the end of an oviduct radially around a central point. In others, ovarioles arise in single fi le off the oviduct, like teeth on a comb.

NUMBER The number of ovarioles per ovary varies with taxon, size, and

life history. All Lepidopteran females have four ovarioles, but many groups tend to be more variable, both within and across species. Variability in ovariole number is particularly spectacular in social insects. Obligately sterile workers in ants can lack ovarioles entirely, and the most fecund queens in ants and termites have about 1200 ovarioles per ovary.

DEVELOPMENTAL ORIGIN The period during which ovarioles form varies widely in insects,

ranging from embryonic development in aphids to the pupal stage in fl ies. In some taxa, the number of ovarioles can be adjusted based on environmental factors. In Drosophila , for example, ovarioles form during the pupal period. This timing provides the opportunity for the number of ovarioles constructed to be adjusted based on previ-ous diet and temperature. In honey bees, however, ovarioles form in early larval development. The number of ovarioles formed is at fi rst the same in future queens and workers. In workers, however, most ovarioles undergo cell death, whereas those in developing queens persist.

SOMATIC TISSUE AROUND DEVELOPING OOCYTES

Each ovariole is made up of both somatic and germ cells. The somatic tissue includes a tubular sheath surrounding all the devel-oping eggs as well as follicle cells around each oocyte. The sheath consists of inner and outer layers. The outer sheath is an open net-work of cells, sometimes containing muscle. The tissue is rich in lipids and glycogen and is metabolically active. Even so, there is no evidence of direct involvement in oocyte development. Tracheoles form part of the outer sheath but do not penetrate below it. The outer sheath can be important in sequestering bacterial symbionts that will be passed on to offspring. The inner sheath is a layer of extracellular matrix. In addition to physical support, the inner sheath can function as a sieve.

A layer of follicle cells surrounds each developing oocyte. Follicle cells are very active metabolically, contributing a variety of materi-als essential to developing eggs. During yolk uptake, follicle cells can separate slightly, allowing vitellogenin-laden hemolymph to contact the oocyte surface directly. The oocyte then can take up vitellogenin and other nutrients. As egg development nears completion, follicle cells secrete the eggshell, which consists of vitelline envelope and layers of chorion.

PATTERNS OF OOCYTE DEVELOPMENT Ovarioles can be categorized based on how oocytes are pro-

duced from stem germ cells ( Fig. 1 ). A stem germ cell produces two daughter cells when it divides; one remains a stem cell and the other becomes a cystoblast. Most commonly, cystoblasts undergo rounds of division but remain connected by intercellular bridges. This proc-ess is called cluster formation. Generally, only one of the daughter cells in a cluster becomes an oocyte, while the remainder degenerate or become nurse cells. The type of oocyte development in which an oocyte is connected to sister cells that contribute to the contents of the egg is termed meroistic.