Some click beetles are large and colorful, but most are under two centimeters long and brown or black, without markings. The adults are typically
nocturnal and
phytophagous, but only some are of economic importance. On hot nights they may enter houses, but are not pests there. Click beetle
larvae, called
wireworms, are usually
saprophagous, living on dead organisms, but some species are serious agricultural pests, and others are active predators of other insect larvae. Some elaterid species are
bioluminescent in both larval and adult form, such as those of the genus
Pyrophorus.
Wireworms Larvae are elongate, cylindrical or somewhat flattened, with hard bodies, somewhat resembling
mealworms. The three pairs of legs on the
thoracic segments are short and the last
abdominal segment is, as is frequently the case in
beetle larvae, directed downward and may serve as a terminal proleg in some species. The ninth segment, the rearmost, is pointed in larvae of
Agriotes,
Dalopius and
Melanotus, but is bifid due to a so-called caudal notch in
Selatosomus (formerly
Ctenicera),
Limonius,
Hypnoides and
Athous species. The
dorsum of the ninth abdominal segment may also have sharp processes, such as in the Oestodini, including the genera
Drapetes and
Oestodes. Although some species complete their development in one year (e.g.
Conoderus), most wireworms spend three or four years in the
soil, feeding on decaying vegetation and the
roots of plants, and often causing damage to agricultural crops such as
potato,
strawberry,
maize, and
wheat. The subterranean habits of wireworms, their ability to quickly locate food by following
carbon dioxide gradients produced by plant material in the soil, and their remarkable ability to recover from illness induced by
insecticide exposure (sometimes after many months), make it hard to exterminate them once they have begun to attack a crop. Wireworms can pass easily through the soil on account of their shape and their propensity for following pre-existing burrows, and can travel from plant to plant, thus injuring the roots of multiple plants within a short time. Methods for pest control include
crop rotation and clearing the land of insects before sowing. Other subterranean creatures such as the leatherjacket grub of
crane flies which have no legs, and
geophilid centipedes, which may have over two hundred, are sometimes confused with the six-legged wireworms.
Clicking ability The ability of click beetles to "click" their bodies, sometimes launching themselves into the air, has been studied in detail. It has three stages—the pre-jump stage, the takeoff stage, and the airborne stage. The beetle is supine, on its back, in the pre-jump stage, and over ~2-3s it rotates its
prothorax (foremost section) down to touch the ground in a bracing position. In the takeoff phase the prothorax rotates rapidly upward in a "snap", launching the beetle off of the ground and ballistically into the air. Crucially, the beetle uses specialized mechanisms to hold itself in the bracing position while its muscles continue to contract, until it releases the tension in one "snap". == Evolution and taxonomy ==