Beetles have biting mouthparts, distinguishing

them from true bugs (Heteroptera), which have

a sucking tube. The key difference between beetles

and superficially similar insects such as bugs and

cockroaches is the fact that Coleoptera have

complete metamorphosis, that is they belong to

the division of insects called Holometabola, which

means that they start as an egg that develops into a

larva, a feeding stage, which then becomes a pupa,

out of which emerges the adult, with its wings and

reproductive organs. Cockroaches and true bugs,

both belonging to Hemimetabola, have immature

stages that resemble smaller wingless versions of

the adult, and they never have a pupal stage.

From a taxonomic point of view, beetles are

well defined, and apart from some Carboniferous

fossils it is usually clear what is and what is not

a beetle. The only exception is the small order

Strepsiptera, called twisted-winged parasites.

Males of these small insects have only the

hindwings developed for flight. The rod-like

forewings seem to serve a balancing function.

The female is parasitic, eyeless, and limbless, and

lives between the abdominal segments of another

insect, usually a bee or wasp. Only the abdomen

is visible, so that the males can mate. Strepsiptera

are often considered the closest living relatives

(Sister Group) of beetles, but some scientists have

good reason to consider that they belong well

inside the beetles, in Tenebrionoidea.

below | Poteriophorus (Curculionidae)

A large weevil rearing up in defense.

The larvae develop in rattan palms

in Southeast Asian forests.

PHOTOS BY KENJI KOHIYAMA