bean weevil, common name for a well-known cosmopolitan species of beetle (Acanthoscelides obtectus) that attacks beans and is thought to be native to the United States. It belongs to the family Bruchidae, the seed beetles. The bean weevil is small, about 1⁄6 in. (0.4 cm) long, and stout-bodied, with a short broad snout and shortened wing covers (elytra). The adults attack legumes either in storage or in the field and may even completely destroy them. The grubs, or larvae, hatch from eggs laid in holes that have been chewed by the female into stored beans or into pods in the field. In heavy infestations there may be two dozen or more newly hatched larvae in one bean. When full-grown, the larvae form pupae in the eaten-out cavity. As many as six generations are produced in a single season, and in storage breeding continues as long as there is available food left in the beans and a warm temperature. The larvae can be killed by fumigation or by heating the seeds to 145°C (63°C) for two hours. Bean weevils are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Bruchidae.
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