Coleoptera: Beetles

The Coleoptera order, or beetles, is one of the largest groups of creatures on the planet. They generally are identified by the presence of hardened fore wings called an elytrum (Figure a.). The hind wings are membranous and are used for flying. Most of the aquatic beetles have piercing mandibles, and they go through complete metamorphosis. The adults carry a bubble of air with them as they swim under the water. The larvae of this order are voracious predators and must be kept in separate containers or they will consume any other samples placed with them. Sometimes, for this reason, the larva are called water tigers. The adults are generally found year round while the larva are almost always found only during spring.

a. b.

The coxal plates and the abdominal segments are used to identify the various families of beetles in their adult form; while the absence or presence of dorsal projections and the shape of the jaw are used to identify the larva.

Coxal plates are flattened structures that extend beyond the coxa, or the first leg segment, of the beetle.

Dorsal projections are tracheal, or gill-like structures, that project, or come out of the top of the creature.


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	Go to the Larva Key Go to the Adult Key The Coleoptera order, or beetles, is one of the largest groups of creatures on the planet. They generally are identified by the presence of hardened fore wings called an elytrum (Figure a.). The hind wings are membranous and are used for flying. Most of the aquatic beetles have piercing mandibles, and they go through complete metamorphosis. The adults carry a bubble of air with them as they swim under the water. The larvae of this order are voracious predators and must be kept in separate containers or they will consume any other samples placed with them. Sometimes, for this reason, the larva are called water tigers. The adults are generally found year round while the larva are almost always found only during spring. a. b. The coxal plates and the abdominal segments are used to identify the various families of beetles in their adult form; while the absence or presence of dorsal projections and the shape of the jaw are used to identify the larva. Coxal plates are flattened structures that extend beyond the coxa, or the first leg segment, of the beetle. Dorsal projections are tracheal, or gill-like structures, that project, or come out of the top of the creature.