Orthoptera

(ör′thäp·tə·rə)

(invertebrate zoology) A heterogeneous order of generalized insects with gradual metamorphosis, chewing mouthparts, and four wings.

---

(Grasshoppers, crickets, and katydids)

Class: Insecta

Order: Orthoptera

Number of families: 43

Evolution and systematics

Until the 1950s and 1960s the definition of the Orthoptera was very inclusive, and many entomologists placed within this order such groups as cockroaches (Blattodea), preying mantids (Mantodea), walking sticks (Phasmodea), and several others. Those representatives of the order that possessed jumping hind legs, such as crickets and grasshoppers, were termed Saltatoria. Currently, most taxonomists consider the order Orthoptera a monophyletic lineage, restricted in its composition to grasshoppers, crickets, katydids, and their closest relatives. Some distinguish between Orthoptera sensu stricto, an order that includes only short-horned grasshoppers and their relatives, and Gryllodea, an order that includes only longhorned grasshoppers, such as crickets and katydids. A division of the Orthoptera into 14 separate orders of insects was also suggested, but this classification scheme never found acceptance among entomologists. For the purpose of this chapter, a classification system that recognizes the order Orthoptera as comprising the suborders Ensifera (long-horned grasshoppers) and Caelifera (short-horned grasshoppers) is adopted. The sister group to the Orthoptera is still not clear; some authors consider them to be most closely related to Phasmodea, but recent molecular data indicate that they may be a sister group to a clade consisting of Phasmodea and Embiidina (web spinners).

The Orthoptera is one of the oldest lineages of insects; the oldest fossils attributed to this order are from the Carboniferous period. The two currently recognized suborders of Orthoptera, Ensifera and Caelifera, probably separated by the late Carboniferous. Most modern families of Ensifera appeared between the early Jurassic and the early Triassic periods. The oldest, still extant family of Ensifera, the Prophalangopsidae, appeared in the early Jurassic. The oldest extant family of Caelifera, the Eumastacidae, appeared in the middle Jurassic, followed by the Tetrigidae and the Tridactylidae at the beginning of the Cretaceous.

The suborder Ensifera (long-horned grasshoppers) is divided into 6 superfamilies and 21 families, with approximately 1,900 genera and 11,000 described species. The largest superfamily of this suborder, Tettigonioidea (katydids or bush-crickets), includes over 1,000 genera and over 7,000 known species; Grylloidea (crickets) includes over 500 genera and 3,500 described species. Other subfamilies of long-horned grasshoppers are the Stenopelmatoidea (Jerusalem and camel crickets), the Gryllotalpoidea (mole crickets), the Mogoplistoidea (scale crickets), and the Hagloidea (grigs or hump-winged crickets).

The Caelifera (short-horned grasshoppers) includes 8 superfamilies, 22 families, nearly 2,400 genera, and over 10,400 described species. The Acridoidea (true grasshoppers and locusts) is the largest superfamily of Caelifera, divided into over 1,600 genera and about 7,200 described species. Other superfamilies of this suborder are the Pyrgomorphoidea (lubber and bush grasshoppers), the Trigonopterygoidea, the Tanaoceroidea (desert grasshoppers), the Eumastacoidea (monkey grasshoppers), the Pneumoroidea (bladder grasshoppers), the Tetrigoidea (grouse or pygmy grasshoppers), and the Tridactyloidea (pygmy mole crickets and sandgropers).

Physical characteristics

Most species of the Orthoptera are large- or medium-sized insects. Body lengths of less than 0.4 in (10 mm) are uncommon, while many exceed 2 in (50 mm) in length, with some having bodies over 3.9 in (100 mm) long and a wingspan of 7.9 in (200 mm) or more. The smallest Orthoptera are antassociated crickets (Myrmecophilus and other genera), whose body length rarely exceeds 0.08 in (2 mm); the largest are katydids of the genera Phyllophora and Macrolyristes. The heaviest of all Orthoptera (and also the heaviest living insect) is the New Zealand giant weta (Deinacrida heteracantha), with a recorded body weight of 0.16 lb (71 g).

Orthopterans are hemimetabolous insects, with larvae resembling adult forms in their general appearance but lacking fully developed wings and reproductive organs. The overall body shape varies dramatically depending on the lifestyle of the species. Grass inhabitants, such as those of the genus Lepacritis, generally tend to have slender, stick- or bladelike body shapes, while arboreal species, such as Steirodon careovirgulatum, are often leaf-shaped. Several groups of desert grasshoppers are perfect mimics of pebbles and moss, and lichen mimicry is common among species inhabiting high-elevation tropical cloud forests, such as Championica montana.

The mouthparts of orthopterans are of the chewing/biting type. The head is hypognathous (mouthparts pointing down), rarely prognathous (mouthparts pointing forward); the antennae are usually long, threadlike, consisting of fewer than ten to several hundred articles. The pronotum, the part of the body immediately behind the head, is usually large, often shieldlike, and in extreme cases covers a large part (as in many katydids) or the entire body of the insect (as in pygmy grasshoppers). The front and middle legs are cursorial, or adapted for walking, yet in some cases the front pair of legs may be modified for digging (as in mole crickets, pygmy mole crickets, sandgropers) or both the front and middle pairs may be modified for grasping (as in predatory katydids). In some orthopterans (most katydids and crickets) the front legs have tibial auditory organs (the ear). The hind legs of most orthopterans are saltatorial, or modified for leaping, with large, muscular femora and long, slender tibiae. Some grasshoppers can perform repeated leaps of 8.5 ft (2.6 m) without any obvious signs of fatigue. This is possible primarily because of the presence of the protein resilin in their back legs. Resilin has superb elastic properties, with a 97% efficiency in returning stored energy. This allows for an explosive release of energy that catapults the insect, a task impossible with muscle power alone. Certain groups of orthopterans, especially those leading a subterranean life, lost their ability to jump, and their hind legs resemble typical cursorial legs.

The wings of orthopterans are either fully developed or reduced to various degrees. Wing polymorphism, or the occurrence of individuals with well-developed and reduced wings within the same species, is not uncommon. The forewings are somewhat thickened, forming leathery tegmina. In most katydids and crickets, parts of the tegmina are modified for stridulation. The hindwings, when present, are fanlike, folded under the first pair in the resting position. The hindwings are often longer than the tegmina and protrude behind their apices. The wing buds of larval stages are always positioned in such a way that the second pair of wings overlaps the first, whereas in adult individuals of micro- and brachypterous species, the first pair of wings always overlaps the second, despite their nymphal appearance. The base of the abdomen in grasshoppers has lateral auditory organs known as abdominal tympana. Most female orthopterans have a prominent ovipositor at the end of the abdomen, derived from the eight and ninth abdominal segments. Katydids and crickets usually have well-developed ovipositors that are sword-, sickle-, or needle-shaped, whereas female grasshoppers and their relatives usually lack a long, external ovipositor.

Body coloration of species of the Orthoptera varies greatly, usually being cryptic, thus resembling the species' immediate surroundings. Arboreal forms are mostly green, often exhibiting a remarkable similarity to leaves, both fresh and those in various states of decomposition. Grass-inhabiting species tend to be either brown or yellow, whereas grasshoppers found in sandy habitats have the coloration of the substrate. Aposematic, or warning coloration, is rare, most often found in toxic or distasteful grasshoppers of the families Pyrgomorphidae and Romaleidae.

Distribution

Orthopteran species occur in nearly all parts of the world and in almost all habitats where insects are found. They are absent only from the polar regions of the globe, the oceans, and extreme alpine zones. The highest species diversity is present in the tropical and subtropical areas, although dry temperate zones, such as southern Europe, the southwestern United States, or Western Australia show remarkably high species diversity of the Orthoptera. Many taxa of this order, including entire families or even superfamilies, show a high degree of endemicity. Two superfamilies of the Orthoptera are very restricted in their distribution: the Tanaoceroidea are found only in the southwestern deserts of North America, the Pneumoroidea occur only in arid zones of southern Africa. The continent of Australia has proportionately the highest number of endemic higher taxa, such as the family Cooloolidae (Cooloola monsters), several subfamilies (including Phasmodinae and Zaprochilinae), and many tribes (including Kakaduacridini and Praxibulini). The island of Madagascar also has a number of endemic taxa, such as the family Malgasiidae (Malagasy crickets), the tribe Aspidonotini (Malagasy helmet katydids), and a very large number of genera and species, whereas New Guinea is home to the subfamily Phyllophorinae (giant helmet katydids). The Caribbean island of Hispaniola has most of the known species of the katydid tribe Polyancistrini. Grasshoppers of the families Lithidiidae, Pneumoridae, and Charilaidae are restricted to southern Africa, Ommexechidae are known only from South America, and Xyronotidae have been found only in Mexico.

On the other hand, some taxa exhibit very wide distribution patterns. Meadow katydids of the genus Conocephalus are found on all continents and most islands, from the subarctic circle to the equator. Even individual species can be cosmopolitan, as is the case of crickets Gryllodes sigillatus and Acheta domesticus (both species are associated with human domiciles), and some grasshoppers (including Tetrix subulata) have Holarctic distribution.

Habitat

Members of the order Orthoptera inhabit virtually all terrestrial habitats, from the rock crevices of the littoral zone of the oceans, subterranean burrows, and caves, to rainforest treetops and peaks of the alpine zones of mountain ranges.

There are few aquatic forms, such as Paulinia acuminata, among the Orthoptera, but many are associated with marshes and other semi-aquatic environments. Reed beds are home to numerous conehead katydids (including Conocephalus, Ruspolia, and Pyrgocorypha), while on muddy banks of rivers, both pygmy grasshoppers (Tetrigidae) and pygmy mole crickets (Tridactylidae) occur. The true mole crickets (Gryllotalpidae) and sandgropers (Cylindrachetidae) are perfectly designed for life underground, where they dig tunnels with their enlarged, shovel-like front legs, and feed on insect larvae and earthworms.

Meadows and savannas are populated by hundreds of species of orthopterans adapted to life among blades of grass. Many of these forms, especially some katydids (including Megalotheca and Peringueyella) and grasshoppers (including Acanthoxia, Leptacris, and Acrida) have body shapes that perfectly mimic the blades and stalks of these plants. Deserts of the world also have unusually rich faunas of orthopterans, with many taxa, such as Comicus and Urnisilla, showing adaptations to life in fine sand. Others, such as Trachypetrella and Lath-icerus, prefer rocky deserts, perfectly blending in among pebbles. A number of orthopteran taxa can be found in caves across the globe. Most troglophilous species belong to camel and cave crickets (Rhaphidophoridae) or various families of true crickets (Gryllidae, Phalangopsidae, and Mogoplistidae), although one species of katydids, the Cedarberg katydid (Cedarbergeniana imperfecta), was recently discovered in a cave in South Africa. A few species of crickets, such as Myrmecophilus, are inquilines in ant colonies, and some, including Tachycines and Acheta, are associated with human habitats, such as greenhouses or basements of houses.

The greatest diversity of the Orthoptera, however, is found in tropical forests, both dry and humid. Thousands of species of katydids, crickets, and grasshoppers have already been described from forest habitats, ranging from crickets, such as Luzara and Eneoptera, in the forest-floor litter, to katydids, such as Sphyrometopa and Euthypoda, on low understory plants, to grasshoppers, such as Ommatolampis and Eumastax, in the forest canopy. Yet thousands more still await discovery, even as large portions of their habitat are destroyed at an accelerating rate.

Behavior

The circadian rhythms of activity among the Orthoptera vary greatly from group to group. Diurnal activity is prevalent in short-horned grasshoppers. During the day most grasshoppers and locusts feed and mate, reserving the night for activities that would be very dangerous during the day, such as molting or laying eggs. The North American grasshopper Cibolacris parviceps is one of the few members of the Caelifera that prefer to feed at night. The reverse is true for katydids and crickets, with most species choosing nocturnal activity. In temperate zones, a greater proportion of species of crickets and katydids are active during the day than in the tropics, where few species can be found stridulating or feeding before dusk. An interesting case of different behavioral patterns exhibited during different times of day is a wasp-mimicking katydid Agacris insectivora from Central America. These black and orange katydids are excellent mimics of large pompilid wasps of the genus Pepsis. During the day these harmless katydids move in a jerky, wasplike fashion, rapidly flickering their orange-tipped antennae. They are not afraid to be seen, in fact they prefer to forage in well-lit gaps in the understory of lowland rainforests. At night, however, when they cannot rely on their pretend warning coloration, their movements are slow and deliberate, similar to those of their cryptically colored relatives.

Most orthopteran species are solitary animals, although gregarious tendencies are common among many crickets (especially members of the family Phalangopsidae), and cave and camel crickets (Rhaphidophoridae). Some crickets (Brachytrupinae) even form small family groups. But the most spectacular example of gregarious behavior in the Orthoptera is that of locusts. Locusts are not members of any particular genus or subfamily of grasshoppers, but the name is applied to those species of grasshoppers that exhibit a clearly defined shift in their behavior, morphology, and physiology, from a solitary to a migratory phase. One example of such a species is the desert locust (Schistocerca gregaria) from arid regions of Africa and the southwest of Asia. During most of the year these insects lead a solitary life, but the spring rains trigger a remarkable transformation in their behavior. Females respond to the rains and the resulting abundance of plant food with a production of larger-than-usual eggs. As the number of insects in the population grows, so does the chance of physically running into another member of their own species. This casual contact triggers a change in the endocrine system of young locusts, which starts to produce hormones that turn these green, cryptically colored insects vividly yellow and black. They begin seeking each other's company and form dense clusters, feeding and marching together. The adults are also different: from sandy gray they turn bright yellow, their wings become longer, and their body larger and more streamlined. Males start producing pheromones that accelerate the development of other individuals, leading to synchronized maturation across the entire population. At the same time, females' pheromones attract other females, causing them to lay eggs close to each other in dense groups. Soon after their final molt, the fully winged adults start flying erratically. One group of flying adults stimulates others to take wing and move off in the direction of the wind. The size of a single swarm can be larger than any other single congregation of organisms on Earth. Desert locust swarms can range in size from 100,000 to 10 billion insects, making them, in terms of the number of individuals, greater than the entire human population. They can stretch from a mere 0.38 mi² (1 km²) to about 385 mi² (1,000 km²) and weigh more than 77,161 tons (70,000 metric tons). In 1794 a particularly large swarm that spread over 1,930 mi² (5,000 km²) succumbed to the wind and drowned in the sea off the coast of South Africa. Within days, a 4 ft (1.2 m) deep wall of insect corpses covered 50 miles (80 km) of the shore.

Swarming behavior is not restricted to the suborder Caelifera. Within the Ensifera certain katydids can produce huge swarms. The North American Mormon cricket (Anabrus simplex; despite the common name it is a large, wingless katydid) forms large marching bands that can bring devastation to crops. Conehead katydids (Ruspolia spp.) occasionally form large flying swarms in Africa.

The single characteristic most frequently associated with grasshoppers and their relatives is their ability to produce sounds. Although less widespread than generally believed, this is nonetheless quite common in some groups of the Orthoptera. The role of sound production is similar in some respects to that of birdcalls: for the attraction of mates, the defense of territory, and to raise the alarm when seized by a predator (release calls). The calls of orthopterans are usually species specific and play a very important role in species recognition. The information in the call may be coded in the form of frequency modulation (the pitch of the call changes through time, a mechanism best known in birds) or time modulation (the pitch of the call remains the same throughout its duration, but its temporal pattern is unique to the species), or a combination of both modes.

The dominant mechanism of sound production in Orthoptera is stridulation, which involves rubbing one modified area of the body against another. Contrary to popular belief, no orthopterans produce sound by rubbing their hind legs against each other. Katydids (Tettigoniidae) and crickets (Grylloidea) produce sound by rubbing a modified vein (the stridulatory vein) of one tegmen (front wing) against a hardened edge of the second tegmen (the scraper). The stridulatory vein is equipped with a filelike row of teeth, the number of which varies from a few to a few hundreds. In most katydids, the stridulatory area is situated at the base of the tegmina, except in short-winged species, such as Thyridoropthrum, where it covers their entire surface. In crickets, virtually the entire surface of tegmina is modified for stridulation. As a rule, katydids have the stridulatory file situated on the left tegmen and the scraper on the right one; in crickets, the situation is reversed. A membranous area at the base of the tegmen, the mirror, amplifies the sound. In addition, some species of katydids, such as Thoracistus and Polyancistrus, use their enlarged, shield-like pronotum as an additional sound amplifier. Crickets, generally lacking the enlarged pronotum, use other methods of sound amplification, such as singing from burrows, the shape and size of which is attuned to boost certain frequencies (Gryllotalpa), or using the surface of a leaf for the same purpose (Oecanthus). The ability to stridulate is restricted almost exclusively to males, although in many groups of katydids, such as Phaneropterinae, Pseudophyllinae, and Ephippigerinae, females respond to the male's calls by producing short calls themselves. Their sound apparatus is different from that of the males, and is usually quite simple, lacking the sophisticated mechanism for sound amplification. In addition to tegminal sound apparatus, a few groups of katydids have other mechanisms of stridulation. For example, all members of the Australasian subfamily Phyllophorinae lack the typical wing stridulation and produce sound by rubbing their hind coxae against modified thoracic sterna. Mandibular sound production occurs in some members of Mecopodinae.

Grasshoppers use the same principle of stridulation, but instead of rubbing their tegmina against each other, they produce sound by rubbing the inner surface of the hind femur against one of the veins of the tegmen. In the slant-faced grasshoppers (Gomphocerinae) the inner surface of the femur possesses a file of small knobs and the vein on the tegmen acts as the scraper. In band-winged grasshoppers (Oedipodinae), the vein has a row of pegs and the femur plays the role of the scraper. In addition to these two principal mechanisms, some grasshoppers stridulate by rubbing their hind legs against the sides of the abdomen (Pamphagidae) or by kicking their legs feet against a modified area at the apex of the tegmen (Stethophyma). Australian false mole crickets (Cylindrachetidae) have a stridulatory file at the base of their maxillary palps, and some species of pygmy mole crickets (Tridactylidae) produce sound by rubbing a modified vein on the dorsal side of the tegmen against another vein at the base of the hindwing.

The sound frequencies produced by orthopterans during stridulation vary, from a few kHz in most crickets and grasshoppers, to well above 100 kHz in some katydids. Cricket calls are characterized by their tonal purity, with most energy of the call allocated within a narrow range of frequencies. Katydid calls vary from tonally pure (although often well above the human hearing range) to broad, noiselike signals. Grasshoppers produce mostly broad spectrum, noiselike calls. Unlike vertebrates, many orthopterans produce time-modulated rather than frequency-modulated signals. Crickets are a notable exception, and most species produce melodious, birdlike, frequency-modulated chirps.

In addition to stridulation, some grasshoppers crepitate, or make a crackling sound, in flight. In this case the sound is produced by rapidly flexing the hind wings while in the air. This behavior is especially common among band-winged grasshoppers (Oedipodinae) and plays an important role in courtship and territorial displays.

A few members of normally acoustic orthopterans have lost their ability to produce airborne signals and instead have developed a number of substitute mechanisms of substrateborne communication. Males of the oak katydids (Meconema) lack the typical tegminal sound apparatus, and instead produce sound by drumming with their hind legs against tree bark. Similar drumming behavior, although still accompanied by the typical stridulation, is a component of the courtship behavior of the pitbull katydid (Lirometopum). Males of the cricket Phaeophilacris spectrum have lost their ability to stridulate, and instead signal by rapidly flicking their tegmina back and forth while holding them in a vertical position. The near-field motion is detected by the cerci of the female cerci, rather than by her ears. Despite having a fully developed stridulatory apparatus, many neotropical members of the katydid subfamilies Pseudophyllinae and Conocephalinae spend little or no time stridulating, relying instead on substrateborne tremulations. In this case, a male stands rigidly on a leaf or stem of a plant and violently shakes his entire body. The low-frequency waves are then transmitted along the branches of the plant. The reason for this behavior is unclear, although a few explanations have been proposed. The most widely accepted of these is the avoidance of predation in the case of foliage-gleaning bats that are known to use insect sounds to locate their prey. Others include eluding satellite males (nonsinging males of the same species trying to intercept a female), avoiding of parasitoid flies, and helping females locate males on multibranched plants. Thanks to the rapid development of recording techniques in recent years, many groups of orthopterans previously believed to be silent appear to employ a number of techniques of substrate communication.

Feeding ecology and diet

The food preferences and foraging behavior of orthopterans are as diverse as their habitats. Virtually all Caelifera (short-horned grasshoppers) are herbivorous, with only a few observations indicating that under some conditions, such as overcrowding or dehydration, grasshoppers may attack each other, especially molting or injured individuals. However, in the great majority of cases grasshoppers feed on leaves and other parts of plants. Many savanna and grassland species are obligatory grass feeders, while arboreal forms feed on tree leaves or the lichens and mosses covering branches. Most grasshoppers are polyphagous, feeding on a variety of species of plants. However, a number of taxa, especially those in the Neotropical subfamilies Ommatolampinae and Rhytidochrotinae, are restricted to feeding on single or only few species of plants, frequently those with high levels of toxic secondary compounds, such as the Solanaceae. Bootettix argentatus is the only North American grasshopper known to be restricted to feeding on a single plant species, in this case the creosote bush (Larrea tridentata). South American grasshopper (Paulinia acuminata) specializes on the giant salvinia (Salvinia molesta), a serious aquatic weed species, and has been used, rather unsuccessfully, in biocontrol efforts to eradicate this plant in Africa, Southeast Asia, and Australia. Pygmy grasshoppers (Tetrigidae) are some of the few insects that feed on mosses and lichens.

Ensifera (katydids, crickets, and their relatives) range from herbivorous, to omnivorous, to strictly predaceous. Some katydids specialize on somewhat unique food sources, for example, members of the Australian genus Zaprochilus feed exclusively on pollen and nectar of flowers. Others, such as many species of the genera Neoconocephalus and Ruspolia, feed mostly on seeds of grasses, whereas many members of the subfamily Phaneropterinae specialize in eating broad leaves. One of a few katydids feeding on pine trees and other conifers is Barbitistes constrictus from Europe.

Most katydids and crickets, however, are opportunistic in their culinary practices and feed on a wide range of organic material. For example, the Central American rhinoceros katy-did (Copiphora rhinoceros) is known to feed on flowers, fruits, hard seeds, caterpillars, other katydids, snails, frog eggs, and even small lizards. Strictly predaceous katydids employ both the "sit-and-wait" strategy (Saginae) or actively forage and hunt living insects (Listroscelidinae). Specialized predatory species usually show distinct modifications of their front and middle legs, which may be very long and equipped with sharp spines to facilitate grasping and holding their prey. Some raspy crickets (Gryllacrididae) also actively search for insect prey by rapidly running along branches and grasping any sitting insect they encounter. Crickets and cave crickets tend to be generalists in their culinary preferences, but also exhibit tendencies to feed on live prey; tree crickets (Oecanthus) are known to feed on aphids. Some mole crickets have a unique behavior among orthopterans (and insects in general) of gathering and storing germinating seeds in circular chambers below ground for later consumption.

Reproductive biology

The courtship and mating behaviors of orthopterans are some of the most complex and fascinating spectacles of the insect world. As well as sound production, many species employ visual, tactile, and olfactory signals in their mating strategies. Visual communication is especially well developed in the predominantly diurnal grasshoppers, where males often have bright, species-specific markings on different parts of their body, and display them in carefully choreographed sequences during courtship. Grasshoppers of the genus Syrbula are champions in this respect, and males of some species, in addition to calling, perform a dance consisting of 18 distinct movements. The visual signals employed by many diurnal grasshoppers include flight displays, in which males flash their colorful hind wings (this is sometimes accompanied by crepitation), flagging with distinctly colored hind legs, and displays involving brightly colored, and often enlarged antennae. Courtship in katydids and crickets relies less on visual signals and more on sound and chemical cues, which are more appropriate for these mostly nocturnal animals. In both groups, males sometimes produce two types of calls, a long-range advertisement call and a more quiet, courtship song, which is performed only in the presence of a female. Female in some species may reply using either airborne signals or tremulation.

Chemical communication in Orthoptera has been little studied, but there is evidence that at least some species employ it during courtship. Females of the New Zealand giant weta produce a musky substance used by males to locate females; male camel crickets of the genus Ceuthophilus have thoracic glands that may also play a role in courtship. The field crickets Teleogryllus comodus use pheromones covering the female antennae to initiate courtship. Some other crickets use airborne pheromones in locating members of the opposite sex.

Copulation in orthopterans involves the transfer of a spermatophore, or sperm sac, which in some groups is accompanied by the spermatophylax, a large packet of nutritious proteins. The size of the spermatophylax can approach 60% of the male's body mass, making it an extremely costly and significant contribution to egg production. This causes the males of many species to be quite choosy when selecting their mating partners, and under certain circumstances, the females may compete for males, a role reversal remarkably rare in the animal world. Some male orthopterans also allow females to feed on parts of their own bodies during copulation. Males of grigs (Cyphoderris) have their hindwings modified into thick, fleshy lobes, the sole purpose of which is to be eaten by the female during copulation. Males who have already mated once and lack these courtship "snacks" must resort to other methods for holding the female's attention. They instead use the "gin trap," a complex system of cuticular modifications whose role is to hold the female's abdomen firmly in place during copulation. Female tree crickets (Oecanthus) feed on the males' thoracic glands during copulation, and in some crickets of the subfamily Nemobiinae, the females feed on enlarged spines on males' hind tibia. Males of other orthopterans, lacking such tasty incentives, must rely on their strong grasp or modified cerci at the end of their abdomen to hold the female during copulation.

Oviposition takes place in a variety of substrates, such as soil, plant tissues, or rock crevices. In some cases, eggs are protected from desiccation by a foamy mass produced by the female. Larvae usually hatch within a few weeks or months, but sometimes the eggs undergo a yearlong, or longer, diapause. Few orthopterans display any kind of parental behavior, although some crickets (Anurogryllus) lay eggs in burrows guarded by the female. Female mole crickets (Gryllotalpa) not only lay eggs in special egg chambers underground, but also actively care for the eggs by licking and removing fungal spores from their surfaces. The hatchlings stay with their mother for a few weeks before dispersing.

Conservation status

As is the case with most invertebrate taxa, there is little information about individual species and population sizes of the Orthoptera on which to precisely assess their conservation status. As of 2002, the IUCN Red List included 74 species of the Orthoptera. Two of these species, the central valley grasshopper (Conozoa hyalina) and Antioch dunes shieldback (Neduba extincta), are listed as Extinct, and the Oahu deceptor bush cricket (Leptogryllus deceptor) is listed as Extinct in the Wild. Eight species are listed as Critically Endangered, eight as Endangered, and 50 as Vulnerable.

The single most critical threat to the survival of orthopteran species is habitat loss. In central Europe, most populations of the heath bush-cricket (Gampsocleis glabra) are extinct or severely reduced in size due to the loss of the original steppe habitats. Invasive species are also extremely serious factors leading to species decline and/or extinction. For example, in Hawaii, the introduced ants Pheidole megacephala have been shown to severely reduce population sizes of native Laupala crickets, and in New Zealand, native wetas (Deinacridinae) are decimated by introduced rats and other mammals.

Significance to humans

Locusts and grasshoppers have been part of human history from the very beginning of our agricultural tradition. They still pose a great risk for agriculture in many parts of the world, although they are less of a problem now than a few hundreds years ago, thanks mostly to a better understanding of their population dynamics and the application of various chemical and biological control measures. Swarms of desert locusts can range in size from 100,000 to 10 billion insects. The amount of food such a mass of insects requires is staggering: in one day a very large swarm can devour the equivalent of food consumed daily by about 20 million people. Such staggering numbers of plant-feeding insects cause similarly unfathomable devastation to crops, and specialized government agencies worldwide constantly monitor the points of origin and movements of locust swarms. Unfortunately, once the swarms are airborne, little can be done to stop the advancing force. Instead, most of the effort goes toward detecting the most likely areas of swarm formation and eradicating young larvae and eggs. Recently, a promising pathogenic fungus Metarhizium anisopliae var. acridum provided a viable alternative to harmful and costly pesticide treatments by selectively targeting locusts without any harm to other organisms. In addition to locusts, a few species of shield-backed katydids are agricultural pests, the best known being the Mormon cricket of the western United States.

A few cultures have realized the nutritional value of locusts, which in some cases can counterbalance the complete devastation of the crops. The Jewish Torah made an exception to the law forbidding eating any insects by stating "[…] The only flying insects with four walking legs that you may eat are those which have knees extending above their feet, [using these longer legs] to hop on the ground." Some tribes in southern Africa eat locusts boiled or roasted, and grilled locusts are often consumed in Cambodia. Mole crickets (Gryllotalpidae) and some armored katydids (Hetrodinae) are also eaten in some parts of Africa.

Despite the devastation caused by some Orthoptera to agriculture, songs of katydids and crickets had a remarkable impact on the poetry and other arts of China and Japan. The Japanese have listened to and appreciated the calls of various Orthoptera, both those in the wild and those kept in cages as pets, for hundreds of years. This activity was popular with the Japanese court, which probably imported some of the customs associated with orthopterans from China, and with the common people. For the Chinese and Japanese, visiting places known for the abundance and high quality of their singing insects was a seasonal pleasures, such as viewing cherry blossoms and autumn leaf. Even now, selling caged singing crickets and katydids is a thriving business in China, and in Japan it is possible to buy a digital replica of a singing katydid.

There are no venomous species of Orthoptera, although a few species of bushhoppers (Phymateus spp.; Pyrgomorphidae) can be toxic if ingested, as they feed on milkweed and other species of Asclepiadaceae, plants that contain high levels of cardiac glycosides. In southern Africa, where bush-hoppers are common, children sometimes may become seriously ill or even die after eating these candy-colored insects.

Species accounts

Field grasshopper
Suriname clicking cricket
Variegated grasshopper
Beetle cricket
Greenhouse camel cricket
Balsam beast
Long-winged conehead
Speckled bush-cricket
Dead leaf mimetica
Hispaniola hooded katydid
Speckled rossophyllum

Resources

Books:

Field, L., ed. The Biology of Wetas, King Crickets and Their Allies. Oxford: CAB International, 2001.

Gangwere, S. K., et al., eds. The Bionomics of Grasshoppers, Katydids and Their Kin. Oxford: CAB International, 1997.

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

Kevan, D. K. McE. "Orthoptera." In Synopsis and Classification of Living Organisms, Vol. 2, edited by S. P. Parker. New York: McGraw-Hill, 1982.

Otte, D. The North American Grasshoppers, Vol. I. Cambridge, MA: Harvard University Press, 1981. ——. The North American Grasshoppers, Vol. II. Cambridge: Harvard University Press, 1984. ——. The Crickets of Hawaii: Origin, Systematics & Evolution. Philadelphia: The Orthopterists' Society, 1994.Rentz, D. C.F. Grasshopper Country: The Abundant Orthopteroid Insect Fauna of Australia. Sydney: University of New South Wales Press, 1986.

Uvarov, B. P. Grasshoppers and Locusts: A Handbook of General Acridology, Vol. 1. Cambridge, UK: Cambridge University Press, 1966.

Other:

Orthoptera Species File Online [May 12, 2003].

The Orthopterists' Society [May 12, 2003]. .

[Article by: Piotr Naskrecki, PhD]

A related group of generalized insect orders (also known as Orthopteroidea). The group is characterized by gradual metamorphosis, chewing mouthparts, and two pairs of wings, the anterior pair of which is usually thickened and leathery and covers the fanwise folded second pair. Wings are reduced or absent in many species. Common representatives include cockroaches, stick insects, praying mantids, grasshoppers, locusts, and crickets. Food habits range from omnivorous to strictly carnivorous or herbivorous. Habitats are nearly all terrestrial, including arctic-alpine tundra and floating aquatic plants in the tropics. There are no parasitic orthopteroids, but a few species live as “guests” in ant nests. Although most orthopteroids are silent, many of the order Orthoptera Saltatoria (grasshoppers, crickets, and katydids) are outstandingly noisy or musical. The orthopteroids include orders of great economic importance and of considerable research potential. See also Animal communication.

The order Blattodea includes the cockroaches, of which only a few species (illus. a) are important pests of stored products and homes.

Orthoptera. (a) Cockroach (Blatta orientalis). (b) Praying mantis (Stagomantis carolina). (c) Walkingstick (Diapheromera femorata). (From Illinois Natural History Survey)

Mantodea, the order of praying mantises (illus. b), is characterized by raptorial (grasping) forelegs on the elongated prothorax. Most are cryptically colored and some closely mimic sticks, leaves, and even flower petals, from which they ambush moving insects.

Phasmatodea, the order of stick and leaf insects (illus. c), are slow-moving, sometimes even mimicking the breeze-induced flutterings of their models. Most temperate species are wingless, but many tropical forms have weakly powered wings that may resemble leaves or corrugated bark. All walkingsticks are herbivorous. Many species of phasmids occur only as females.

The order Orthoptera Saltatoria has enlarged hind femora adapted for jumping. There are many families, most of which are grouped as acridoids (short-horned grasshoppers), tettigonioids (long-horned grasshoppers), or grylloids (crickets). Most are herbivorous, but omnivores and carnivores are known.

1. Acridoids. Most temperate species of short-horned grasshoppers belong to the family Acrididae. Antennae are less than half the length of the body. The ovipositor has outwardly pointing hooks. Most species are diurnal and cryptic, some mimicking stones, debris, and grass stems. The plague locusts, Locusta migratoria, several species of Schistocerca, and others migrate hundreds of miles from the outbreak center in some years to devastate thousands of acres of crops in the tropics and subtropics.

2. Tettigonioids. Antennae are usually longer than the body in the family Tettigoniidae. Most species are nocturnal and the males' stridulation can be very loud, especially when chorusing. The ovipositor is long and sword-shaped. Meadow grasshoppers and katydids are usually cryptically shaped and colored. A major western North American pest is the flightless Mormon cricket.

3. Grylloids. True crickets (Gryllidae) are ground-, tree-, or bush-dwelling, relatively chunky insects with antennae longer than the body and a needle-shaped ovipositor. The mole crickets (Gryllotalpidae) are serious pests of tropical crops.

Several features of the rock crawlers, order Grylloblattodea, including roachlike legs and asymmetrical male genitalia, indicate that they are a relict order of some ancient orthopteroid group (illus. i), but the ovipositor is katydidlike. The rock crawlers are wingless, and there is probably only a single genus, Grylloblatta, although the Japanese and Siberian species are sometimes given separate status. They prefer temperatures close to freezing. See also Insecta.

---

An order of insects of little direct importance to veterinary science except that some act as the intermediate host for some worms. Includes grasshoppers, crickets, cockroaches.

IN BRIEF: n. - An order of insects with mouthparts adapted for chewing; grasshoppers and locusts.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)