Grasshoppers, Crickets, and Katydids: Orthoptera
GRASSHOPPERS, CRICKETS, AND KATYDIDS: OrthopteraBEETLE CRICKET (Rhabdotogryllus caraboides): SPECIES ACCOUNTS
VARIEGATED GRASSHOPPER (Zonocerus variegatus): SPECIES ACCOUNTS
GREENHOUSE CAMEL CRICKET (Tachycines asynamorus): SPECIES ACCOUNTS
BALSAM BEAST (Anthophiloptera dryas): SPECIES ACCOUNTS
LONG-WINGED CONEHEAD (Conocephalus discolor): SPECIES ACCOUNTS
DEAD LEAF MIMETICA (Mimetica mortuifolia): SPECIES ACCOUNTS
HISPANIOLA HOODED KATYDID (Polyancistrus serrulatus): SPECIES ACCOUNTS
The Orthoptera include grasshoppers, crickets, katydids, and their relatives. Most orthopterans are medium to large in size, ranging in length from 0.4 to 3.9 inches (10 to 100 millimeters). The smallest species are crickets that live with ants; they are rarely more than 0.08 inches (2 millimeters) in length. The largest species are the katydids, each with wingspans of 7.9 inches (200 millimeters) or more. The heaviest orthopteran, which also happens to be the heaviest insect in the world, is the New Zealand giant weta that weighs in at a hefty 0.16 lb (71 g).
The head is distinct and has powerful chewing mouthparts that are usually pointed downward. The antennae (an-TEH-nee) are relatively short and thick, with 30 or fewer segments (as on grasshoppers), or long and threadlike, with more than 30 segments (as for crickets and katydids).
The midsection of the body is only the first part of a three-part thorax. This section of the body is sometimes enlarged and extends back over part or all of the body. The wings, if present, number four and cover the rest of the thorax. The forewings are slightly thickened and are supported by a network of veins. In most katydids and crickets, the bases of the forewings have special structures that resemble a scraper and a file. These structures are rubbed against one another to produce buzzes, chirps, and clicks. The hindwings, if present, are folded fanlike under the forewings when the animal is at rest. They are sometimes longer and stick out just beyond the tips of the forewings. Larvae (LAR-vee), or young form of the animal, closely resemble the adults but lack fully developed wings and reproductive organs. The developing wings are positioned so that the second pair of wings partially cover the first. In adults the forewings always cover the hindwings, even in species that never fully develop wings.
The wings of many grasshoppers are colored and textured so that they blend in with leaves, sticks, rocks, gravel, or sand in their habitat. Katydids mimic living and dead plants with leaflike wings and colors. A few grasshoppers have bright and distinctive patterns, or aposematic (APO-se-ma-tik) coloration, on their wings and bodies that warns predators that their bodies are filled with bad-tasting chemicals.
The front and middle legs are usually slender and are used for walking. In mole crickets and other species that like to dig, both the front and middle legs are rakelike for moving soil. The legs of katydids that eat other insects are spiny and used to capture and hold on to their prey. In crickets and katydids, each front leg has an ear. Grasshopper ears are located on the sides of the abdomen just behind the thorax. The hind legs are usually large, muscular, and used for jumping. Digging species no longer have the need to jump, so their hind legs more closely resemble the other legs.
The abdomens of most female crickets and katydids have a distinctive egg-laying device, or ovipositor (O-vih-pa-zih-ter). The ovipositor is either hooked, swordlike, or needlelike and is used to place eggs inside rotten wood or deep in the soil. Grasshoppers lack this kind of egg-laying device.
Grasshoppers, crickets, and katydids are found on all continents and islands, except Antarctica. There are about 21,400 species of orthopterans worldwide, with about 3,000 species in the United States and Canada.
Grasshoppers, crickets, and katydids inhabit virtually all terrestrial habitats, from rocky coastlines, underground burrows, and caves, to the tops of trees in rainforests and high mountain peaks. Others prefer wetlands, with some species living right on the shores of ponds, streams, lakes, and rivers. A few species actually live in water. Many species live in meadows and deserts. Still other species are very particular about where they live; some specialists take shelter in ant nests, while others are at home in greenhouses and basements.
Most orthopterans eat plants, but a few species will supplement their diets with living or dead insects. Nearly all grasshoppers are plant feeders, or herbivores (URH-bi-vorz). However, when there is a lack of water, or too many individuals in a small area, some grasshoppers may begin to eat each other and scavenge their dead. Herbivores will eat all parts of grasses, weeds, shrubs, and trees. Some species living in trees will also eat lichens (LIE-kuhns) and mosses. Most species will eat whatever plants are available, but a few will eat only one kind of plant or a few closely related species.
Many species of crickets, katydids, and their relatives are also herbivores. At least one Australian katydid feeds only on the pollen and nectar of flowers. Others prefer grass seeds or just leaves. Very few katydid species feed on the needles of pines and other cone-bearing trees. Some species are omnivores (AM-nivorz), animals that eat both plant and animal foods, and will eat whatever is available to them. Although crickets and cave crickets tend to be omnivorous, they seem to prefer feeding on live insects. Tree crickets will eat aphids. Omnivorous mole crickets are the only insects that gather and store seeds in underground chambers. They will then use the young sprouts as food. The Central American rhinoceros katydid will eat flowers, fruits, and seeds, as well as caterpillars, other katydids, snails, and frog eggs. They have even been known to attack small lizards.
A few orthopterans are strictly meat-eaters, or carnivores (KAR-ni-vorz), and eat the flesh of other insects. These katydids either use a "sit-and-wait" strategy to ambush their prey or actively hunt for food. Prey is captured and held with the aid of sharp spines on their front and middle legs.
BEHAVIOR AND REPRODUCTION
Most grasshoppers feed and mate during the day but molt and lay their eggs at night. The majority of katydids and crickets tend to be active at night, especially in the tropics. However, a wasp-mimicking katydid from Central America is active during the day. These katydids are black and orange and strongly resemble the large tarantula hawk wasps. These harmless katydids not only look like wasps, they act like them too. They are found in sunny openings in lowland rainforests, where they move in a jerky, wasplike fashion, constantly twitching their orange-tipped antennae. At night their behavior changes. Unable to rely on their wasplike appearance to fool their enemies in the dark, their movements become slow and deliberate, just like the katydids that resemble leaves.
Most orthopterans tend to live by themselves, except during the mating season. However, many crickets are often found in small groups. Locusts sometimes form massive swarms made up of hundreds of thousands, even billions, of individuals. Locusts are grasshoppers that show a definite change in their behavior, shape, and vital body functions as they go from living alone to joining other individuals in swarms. Other groups of orthopterans also form swarms. The North American Mormon cricket is actually a large, wingless katydid that regularly forms large groups that can totally destroy any crops in their paths. African conehead katydids also form large flying swarms.
One of the most common features associated with many orthopterans is their ability to produce sounds. There are few places during the warmer months where the daytime rasps and snaps of grasshoppers or the nocturnal chirps, clicks, and buzzes of katydids and crickets cannot be heard. These calls are produced to claim territory, attract mates, or to sound an alarm. The volume and pitch of the calls, usually produced by males, are unique to each species and helps them to recognize one another.
Contrary to popular belief, none of these insects produces sounds by rubbing its legs together. Males produce sounds by rubbing the bases of their wings together or their hind legs against the edges of the wings. Crickets and katydids generally rub a set of tiny pegs, or file, located at the base of one wing against a strong ridge, or scraper, on the other wing to produce buzzes, chirps, and clicks. A few species grind their jaws together to produce sounds, while others rub the bases of their legs against the underside of the thorax. The sound produced is amplified by a smooth membrane located on the base of the wings.
Grasshoppers "sing" by rubbing the inside surface of their jumping legs against the edges of their forewings. They can amplify the sound by expanding their wings. Some grasshoppers also make a crackling sound when they fly. The sound is produced by rapidly bending their hind wings while in the air. The crackling sound is common among band-winged grasshoppers and is used in courtship and territorial displays.
Courtship and mating behaviors involve sight, sound, smell, and touch. Grasshoppers use mostly visual communication. Males often have bright markings on different parts of their bodies and wings that are unique to their species. They instinctively display these features as if they were in a highly practiced dance routine. Male crickets and katydids sometimes produce two different kinds of calls. The first is used as long-range advertising to attract a female. The second is quieter and is used in courtship when the female is nearby. In a few species, the females may respond with a call of their own. Courtship in katydids and crickets depends not only on sounds but also on smells. Odors, or chemical signals, make sense since they are mostly active at night and cannot see each other, but their use of smells is not very well known. A few species, such as female giant wetas in New Zealand, produce pheromones (FEH-remoans) and other odors to attract males.
Males place the sperm packet directly into the body of the female. The sperm packet may weigh as much as 60% of the total body weight of the male. In some species the males have special organs that are eaten by the female while they are mating. In other species males have special projections on their abdomens that are used to hold the female while they mate.
Most female crickets and katydids use their hooked, needle-like, or swordlike ovipositors to place eggs out of harm's way deep into soil or rotting wood. Female grasshoppers lack external ovipositors, but have thickened valves on the tips of their abdomen. They drill through the soil using hardened plates on the tip of their abdomens and deposit them deep in the soil or rotten wood by stretching the entire length of their abdomen into the hole. Sometimes the eggs are placed in a foamy mass that helps to keep them from drying out.
The larvae usually hatch within a few weeks or months, sometimes longer. They strongly resemble the adults when they hatch but lack developed wings and reproductive organs. Most orthopterans do not care for their young, although in some species the mother will guard her eggs. Mole crickets lay their eggs in special chambers and lick them to prevent them from becoming spoiled by fungus. After hatching, the young mole cricket larvae remain with their mother for a few weeks before going out on their own. Larvae develop gradually, molting six to ten times before reaching adulthood.
ORTHOPTERANS AND PEOPLE
Plagues of crickets and grasshoppers have invaded homes and ravaged crops for centuries.
In Africa and Asia locusts are still a serious threat to crops, but the problem has decreased over the years as scientists now have a better understanding of reasons for their population explosions and have developed various control measures. However, once the swarms become airborne, there is little that can be done to stop them. A promising fungal disease in locusts has proven to provide yet another way of controlling them without using dangerous and expensive chemicals. Other species of locusts, Mormon crickets, and some katydids are sometimes serious agricultural pests in the western United States.
In many parts of the world orthopterans are important in the human diet and are sometimes considered to be a real treat. Tribal people in southern Africa eat locusts boiled or roasted, and grilled locusts are often consumed in Cambodia. Mole crickets and some armored katydids are also eaten in some parts of Africa.
Katydids and crickets are very popular in poetry and other arts of China and Japan. Both Chinese and Japanese families vacation in summer to areas with lots singing insects. The Japanese have long appreciated their calls in the wild and often keep them indoors in special cages as pets. Today, selling caged singing crickets and katydids is a thriving business in China, and the Japanese have even designed a digital replica of the katydid's call.
Seventy-four species of orthopterans are listed by the World Conservation Union (IUCN).
A PLAGUE OF LOCUSTS
A single swarm of desert locusts might contain up to ten billion insects and weigh up to 77,161 tons (70,000 metric tons). In 1794 a massive swarm that spread over 1,930.5 square miles (5,000 square kilometers) was blown out to sea and drowned off the western coast of South Africa. A 4-foot (1.2 meters) deep wall of dead insects soon washed up along 50 miles (80 kilometers) of coastline.
Two of these species, the central valley grasshopper and Antioch dunes shieldback, are listed as Extinct, or no longer alive. The Oahu deceptor bush cricket is listed as Extinct in the Wild, or alive only in an artificial environment. Eight species are listed as Critically Endangered, another eight as Endangered, and 50 more species are listed as Vulnerable. Critically Endangered means facing an extremely high risk of extinction in the wild. Endangered means facing a very high risk of extinction in the wild, and Vulnerable means facing a high risk of extinction in the wild.
The single most important threat to all orthoptrans is habitat destruction. This is especially true for species that are found only in small geographic areas. The introduction of ants, cats, and rats, especially on islands such as New Zealand, is a serious threat to many orthopteran species.
Physical characteristics: Beetle crickets are small, black, shiny, and beetlelike. Males and females have short, thick forewings covering only half of the abdomen. The veins on these wings are made up of many straight, parallel veins. Males lack the ability to produce sound with their wings.
Geographic range: Guinea (West Africa).
Habitat: Beetle crickets are found in leaf litter of the lowland and middle elevation rainforests, as well as in termite mounds.
Diet: Nothing is known.
Behavior and reproduction: Almost nothing is known about its behavior or reproduction. It may be associated with termites, but the nature of this relationship is unknown.
Beetle crickets and people: Beetle crickets are not known to impact people or their activities.
Conservation status: This species is likely to be threatened by habitat loss but is not now endangered or threatened. ∎
Physical characteristics: The variegated grasshopper has a yellow-green body 1.4 to 2.2 inches (35 to 55 millimeters) in length, with yellow, orange, white, and black markings. The wings are usually very short, covering only half of the abdomen, but long-winged individuals are also known. Larvae are black with bright yellow speckles.
Geographic range: Variegated grasshoppers are found in sub-Saharan Africa.
Habitat: They live in savannahs, pastures, and agricultural fields.
Diet: They feed on a variety of plants, especially relatives of peas. They take bad-tasting chemicals from these plants and use them in their own body tissues as part of their own defense strategy. The bright colors of these grasshoppers advertise the fact that they taste bad. Because they eat many kinds of plants with little or no bad-tasting chemicals, some grasshoppers may not taste bad at all. For example, they are commonly roasted and eaten by people living in southern Nigeria.
Behavior and reproduction: The larvae feed in groups, forming clusters of tens or hundreds of individuals on a single plant. Both the larvae and adults are slow moving. Even the fully winged adults are reluctant to fly, apparently relying on their bright warning colors to discourage most predators.
Females lay their eggs in foamy egg pods and bury them in the soil.
Variegated grasshoppers and people: They are serious pests of cassava, maize, and other crops in Africa south of the Sahara Desert.
Conservation status: This species is not endangered or threatened. ∎
Physical characteristics: The wingless bodies of greenhouse camel crickets are yellow-brown, spotted, and measure 0.5 to 0.7 inches (13 to 19 millimeters) in length. The legs and antennae are long and slender, giving them the appearance of a long-legged spider. They are very quick and capable of jumping long distances. Females have a long swordlike ovipositor.
Geographic range: Originally from the Far East (probably China), they are now found throughout the world, except in the polar regions.
Habitat: Wild populations once lived in caves, but now most are found in greenhouses and in homes in warm, humid cellars and basements.
Diet: They are omnivorous, feeding on a variety of plant and animal foods, including other insects and plants.
Behavior and reproduction: They are active only at night and spend their days hidden in crevices and under large objects. They are always found in groups.
Females lay their eggs in soil. When the larvae hatch they will join groups of older individuals.
Greenhouse camel crickets and people: They are sometimes a pest in greenhouses, eating young plants. They are a nuisance to people because they are quick, jump unpredictably, and resemble spiders.
Conservation status: This species is not endangered or threatened. ∎
Physical characteristics: The body is green or brown, leaflike, and measures 2 to 2.75 inches (50 to 70 millimeters) in length. Their mouthparts point forward, instead of downward. The legs, antennae, and wings are long and slender.
Geographic range: Balsam beasts are found in New South Wales and Queensland (Australia).
Habitat: They live in coastal wooded suburbs and gardens.
Diet: This species feeds on a wide variety of flowers and trees and is especially fond of garden balsam (Impatiens sp.).
Behavior and reproduction: They are active at night in the tree tops.
Females lay their eggs one at a time in the cracks found on bark, especially near the base of the tree.
Balsam beasts and people: They are sometimes considered garden pests.
Conservation status: This species is not endangered or threatened. ∎
Physical characteristics: The body of a long-winged conehead is light green, with a distinctive dark brown stripe down the back, and measures 0.5 to 0.7 inches (12 to 17 millimeters) in length. The wings are longer than the body, with the hind wings extending beyond the tips of the forewings. The ovipositor is straight and is nearly as long as the body.
Geographic range: They are widespread in Europe and western Asia.
Habitat: Long-winged coneheads live in meadows, marshes, reed beds, and near water.
Diet: This species eats grasses and other plants but will also catch small insects, such as aphids, and caterpillars.
Behavior and reproduction: This day-active species has very good vision. They are very alert and are quick to the other side of a stem or jump when threatened. The call of the male is a soft, continuous buzz.
Females lay their eggs in grass or reed stems. Sometimes they will chew small holes in stems through which they insert their ovipositor. Like the adults, the larvae are light green with a black stripe down the back.
Long-winged coneheads and people: This species does not impact humans or their activities.
Conservation status: This species is not endangered or threatened. ∎
Physical characteristics: Dead leaf mimeticas are excellent mimics of living and dead leaves. Their bodies and wings are green, brown, or a combination of both. The forewings resemble the shape of a leaf and have leaflike veins. They also have small notches cut out of them as if they were leaves that had been nibbled by another herbivorous insect. Hind wings are very small. The female's ovipositor is strongly curved, with a thick, sawlike tip.
Geographic range: They are found in Costa Rica and Panama.
Habitat: The dead leaf mimetica lives in lowlands and middle elevations, from low shrubs to high up in trees.
Diet: This species eats the leaves of various trees.
Behavior and reproduction: Remaining motionless in the trees, this species is impossible to find during the day. It feeds on leaves at night. The males make short, buzzing calls.
The strongly curved ovipositor of females is shaped to penetrate tissues of plant stems where eggs are laid. To lay eggs, the female bends abdomen down and forward until her ovipositor faces forward between her front legs. She then uses her legs to guide the ovipositor and insert it into plant tissue. Eggs are laid individually, left partially protruding from the plant to allow for easy exchange of oxygen for developing embryo.
Dead leaf mimeticas and people: This species is not known to impact humans or their activities.
Conservation status: This species is not now endangered or threatened. They are abundant but could easily be threatened by habitat destruction. ∎
Physical characteristics: The body is usually brown, sometimes green, and measures 1.4 to 2.5 inches (35 to 65 millimeters) in length. Both males and females have a hoodlike plate on top of their midsection. The female's ovipositor is long and sword-shaped.
Geographic range: This species is found in the Dominican Republic (Hispaniola).
Habitat: They live in trees and tall bushes.
Diet: They eat the leaves, fruits, and flowers of a wide variety of plants.
Behavior and reproduction: These hooded katydids are active at night. Both males and females produce loud calls. They spend their days in rolled-up leaves or under loose strips of tree bark.
Females most likely lay their eggs in soil.
Hispaniola hooded katydids and people: This species does not impact people or their activities.
Conservation status: This species is not endangered or threatened. As with most species living in tropical rainforests, they may become threatened by the destruction of their habitat. ∎
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