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Order
COLEOPTERA(Greek, koleos = sheath ; pteron = wing)
Suborders
Adephaga, Polyphaga
Common Names
beetles, weevils, ladybirds
Description
Beetles usually have a strongly stiffened (sclerotised) exoskeleton and frequently possess well developed mandibles. The compound eyes are varied in structure and development but simple eyes (ocelli) are usually absent. Antennae are varied in structure and development. The forewings (those nearest the head) are modified to form hard, protective covers (elytra) for the hind wings. Hind wings are membranous and used for flying. Beetle flight is usually very distinctive with the wing covers (elytra) held stiffly out from the body.
Life Cycle
Larvae are often referred to as "grubs" and usually have 6 legs on the thorax. The larvae always have a hard chitinised head capsule with antennae and mandibles. Pupae have mandibles, but these are immobile. Other pupal appendages (e.g. legs, wings, antennae) may be free or fixed depending upon the species.
Distribution
Members
Beetles - scarabs, click beetles, water beetles, borers of many kinds, dung beetles, all weevils, fireflies, ladybirds, longicorn beetles, Christmas beetles, etc.
Food
Almost every vegetative source has been exploited by a beetle species including flowers, buds, stems, roots, seeds, bark, wood, galls, leaf or forest litter, etc. Dung, fungi and carrion are used by many species. Very few species are parasitic but many are carnivores. Some beetles attack preserved animal products such as hides or leather. The order has been extremely successful in colonising almost every possible habitat.
Importance
Beetles are of extreme importance in the forestry, timber and gardening industries. Enormous damage is done to wood products by boring beetles. Grub stages attack the roots of grass or other plants causing considerable damage. In Europe, the ambrosia beetle acts as a vector of the fungal parasite that causes Dutch elm disease. This disease has destroyed enormous numbers of elm trees all over the European continent. Annually weevils destroy millions of dollars worth of grain or grain products on a world basis. Beetles have been useful for their application as biological control agents: dung beetles assist with the disposal of horse and cattle manure; the weevil (Cyrtobagus sp.) is used to control Salvinia in Australia and Papua New Guinea. Adults and larvae also play an important role in the re-cycling of dead and decaying timber. The organic farming industry encourages beetles such as ladybirds for predation on aphids and similar destructive insects.