Bean weevil

Classification

Primary pest; Grain feeder
Order: Coleoptera
Family: Chrysomelidae
Acronym: AOB

Description

• Adults are 3 to 4 mm long, globular in shape with long legs.
• Elytra do not reach the end of the abdomen, leaving the last terga exposed.
• Last upper abdominal segment is covered with yellowish hair (setae).
• Inner ridge of the ventral margin of the hind femur has three or four "teeth".
• Larvae are white and grub-like, having reduced legs.

Similar species

• Pea weevil (Bruchus pisorum)

Commodities affected

• Beans, broad beans, lentils, chickpea, soybean

Signs of infestation

• Damaged seeds with entrance or exit holes

Damage

• Damage is distinctive with tiny dot-like entrance holes and larger, round exit holes and excavated seed.
• Large populations may reduce stored seed to dust.

How to control

• Control grain insect pests

Geographic range

• Is distributed worldwide
• Is distributed across Canada

Where found

• Primarily attacks stored beans but may attack plants in the field
• Establishes well in heated storages and granaries

Life history

• Adult bean weevils feed on bean plant foliage and seed pods.
• Females lay eggs inside the seed in storage or lays multiple eggs on the surface of a pod in the field.
• Larvae develop in growing or stored bean seeds.
• After pupation within the seed, the adult chews an exit hole through the seed coat.
• In heated storage conditions, the adult bean weevil can emerge at any time of the year and breed continuously.