Bruchid beetle / Dried Bean Weevil (Acanthoscelides obtectus)

Attack by this beetle often starts in growing crops in the field. Female beetles lay eggs on the ripening pods on the crop or among stored beans. Householders may notice bean weevils for the first time on windows and doors as they emerge from stored seeds. They are attracted to light and are attempting to escape. Usually, there is little concern for their presence until a sack of dried beans or peas, especially home grown, is emptied and found full of holes. With beans stored indoors at warm temperatures, bean weevils breed continuously as long as there is food left in the beans. Populations can become very high.

Identification:
Adult beetle: 3-4mm long. The elytra (wing cases) are variegated with yellowish and dark brown patches of hairs. Larvae: 3-4mm long, whitish in colour, crescent shaped with reduced legs. The adult overwinters in stored beans or in the field.

Biology:
Adult females lay single fertilised eggs on the external surface of a dry bean seed. The larva develops in growing or dry stored beans. It bores through the pod to the seed in growing plants. The larva destroys the seed as it forms a chamber inside the bean and then feeds on the bean. The life cycle is completed inside the seed and the adult beetle emerges by pushing the window, which falls off leaving a neat round hole about 2 mm in diameter.

Control:
Control of these insects involves inspection and removal of infested food products, discarding the heavily infested material, repackaging material in new containers, and vacuuming kitchen cabinets, contents of the vacuum cleaner should be disposed of in an outside bin. Food products that need to be retained may be placed in the freezer for several weeks to kill adults and larvae. After cleaning, treat the infested areas using a residual insecticide labeled for crawling insect to ensure that all adult beetles have been killed.

Products to control Bruchid Beetle/ Dried Bean Weevil: