External Structure

Strepsiptera) or the hind wings (Diptera, and some Ephemeroptera and Hemiptera). In these 83

insects the wings, no longer used directly in flight (i.e., to create lift through flapping), are still present but modified for other functions. The modified hind wings, halteres, ofDiptera and male Coccoidea (Hemiptera) are highly developed sensory structures used in attitudinal control (see Figure 14.15). The heavily sclerotized elytra (fore wings) of Coleoptera are mainly protective in function, though they may be secondarily important in control of attitude.

Even in insects that retain two functional pairs of wings there are frequently modifications of these structures for other functions. In many Lepidoptera, for example, the wing margins are irregular and the wings appropriately colored so that when the insect is at rest it is camouflaged. The wings of male Orthoptera are commonly modified for sound production. In crickets and long-horned grasshoppers the hardened fore wings possess a toothed file (the modified cubital vein) and a scraper (a sclerotized ridge at the wing margin). Rapid opening and closing of the wings causes the file on one wing to be dragged over the scraper of the other wing and sound to be produced. In short-horned grasshoppers that sing the file is on the hind femur; the scraper takes the form of ridged veins on the fore wings.

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