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Common Bean Weevil

Acanthoscelides obtectus

Common Bean Weevil, Bean Weevil

A photograph of a bean weevil Acanthoscelides obtectus against a white surface

Acanthoscelides obtectus

by lillolollo. CC BY-SA 3.0

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A Bean Weevil is a small, brown beetle with a high attraction for bean plants. Once emerged from hibernation, they migrate to their first food plant, which can be vetch, pea vine, lupin, alfalfa, and other leguminous cultures. They then move to a secondary host, which can range from haricot bean, soybean and lentils. These beetles can be especially harmful in agriculture. They often migrate to fields of legumes, where they can sometimes reduce the yield by 50-60%. They harm the plant by eating through the seed shells, depleting the contents, before hibernating within the empty shell.
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Traits

It can be difficult to detect a Bean Weevil infestation.
Luckily, its only the larvae that eat bean plants.

Appearance

Bean weevils are small beetles, ranging in size from 2 to 5 mm They range in colour from light to dark brown, with longitudinal spots on their elytra, which has a red posterior border.Eleytra does not cover the abdominal end. and lacks the long snout that is characteristic of true weevils. with yellow-green golden hairs and longitudinal spots from above, light grey hairs from below. Eggs are milky white. Larvae are white with a yellow head during their first instar and white with a brownish head from the second instar. Larvae have bristles and three pairs of legs

Symptoms

Holes in the bean shells. Beans will be empty shells.

Activity

Diurnal

Personality

Order

Coleoptera

Family

Chrysomelidae

Metamorphosis

Complete

Distribution

North America, South America, and the warmer parts of Africa, Asia and Europe.

Biological treatment

A number of parasitoid wasp are associated with the bean weevil larvae. You can attract beneficial insects into your green spaces by planting a selection of indigenous plants, incorporating insect hotels, or by letting some areas grow a little wild.

Attracts

Lupin

Lupinus spp.

Alfalfa

Medicago sativa

Sweet Pea

Lathyrus spp.

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