What are beetles?
Beetles belong to the order Coleoptera, a well-known group of insects that are easily recognizable on account of their hard wing covers (elytra). With more than 350,000 known species, Coleoptera is the largest of all insect orders and displays an enormous variety of form, size and habit. A number of species are a serious pest in crops or stored products. There are many useful beetles as well. For instance, ladybirds contribute to the control of aphids.
Beetles undergo a complete metamorphosis, that is, the larvae do not resemble the adult at all, and must pass through a pupal instar before reaching the adult stage. Larvae have biting mouthparts and mostly feed on the same food as the adults. The pupae do not make a cocoon and will already display many similarities with the adults. The adult beetles usually possess a pair of membranous wings beneath the wing covers. Many species are very capable fliers but others cannot fly at all.
Both larvae and adults of beetles can cause damage to crops. The larvae of some species feed on growing tips and roots or chew and bore into stems, but in other species also feed on leaves. Adult beetles cause damage by feeding on fruits, flower buds and leaves depending on the species.