Seed Beetles-Bruchidae

Seed Beetles-Bruchidae

The Bruchidae are short, stumpy beetles with small, mole heads and small protothoraxes. The tips of the antennae are somewhat flattened and toothed in some species. The wing covers are short and the body is often covered with multicolored hairs. The adult bruchids resemble the leaf beetles of the Chrysomelidae, but the larvae resemble the weevils of the Curculionidae.

The Pea Weevil, Bruchus pisorum, is a common species in this family. Usually black with handsomely decorated, multicolored elytra^ the pea weevil feeds on the pollen of garden and field peas. The female lays her amber-colored eggs on young peapods, and after about nine days the larvae emerge.

At this stage the larvae resemble the larvae of the leaf beetle (Chrysomelidae).

The young larvae bore into the perapod. Each larva then buries itself in a young pea. Inside the pea, the larva undergoes a process akin to hypermetamorphosis in which it loses its legs and takes on the appearance of a Curculionidae larva. Just before it pupates, the larva digs an exit hole through which the new adult will eventually pass. Often, however, this hole is too small and the emerging adult insect remains trapped in the pea.

The Bean Weevil, Acanthoscelides obtectus, is similar in many ways to the pea weevil. It is unusual, however, in that it will attack dried beans, whereas the pea weevil feeds only on fresh peas. Many housewives have seen the tiny gray or olive bean weevil, usually flying around the kitchen window trying to escape. This is a definite sign that somewhere in the house is a sack of dried beans, riddled with tiny exit holes.