Order

CHAPTER

phylum class subclass • order monotypic order suborder family

PHYSICAL CHARACTERISTICS

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.

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