Foreign grain beetle
Ahasverus advena (Waltl)

Order: Coleoptera
Family: Silvanidae
Acronym: AAD

Ecology

The foreign grain beetle is found in both tropical and temperate regions. In Canada, it survives in protected areas in elevators and is usually found in moist, moldy grain.

Damage

The insect feeds on molds on damp grain (1), bread, biscuits and other farinaceous materials. In feeding on moldy grain, it may also damage the germ of the kernels if the relative humidity is over 65%. However, grain injury by this pest is not severe enough to cause economic loss.

Life history

The adult beetle is brown, rounded in shape and about 2 mm long. It resembles the rusty grain beetle, but can be distinguished from it by its club-shaped antennae. The eggs are oval. The larvae are wormlike, cream-colored and reach a length of 3 mm before pupating. Little is known about the life cycle of this insect, but under laboratory conditions and a temperature of 27°C, the transition from egg to adult beetle takes about 3 weeks. Temperature limits for complete development are 20° to 35°C. The insects can only survive in moist, moldy grain and if the relative humidity is over 70%.

Control

Although this insect is not of economic importance, it is often mistaken for the rusty grain beetle because of the similarity in appearance. Both pests can be controlled by cleaning and spraying grain bins with an approved structural insecticide before refilling the bins. Using aeration to both cool and dry grain will mitigate this insect from establishing and reproducing. Ensure grain surface is level before aeration.

Images

Drawing of an adult foreign grain beetle.

Adult foreign grain beetle.

Larva of a foreign grain beetle.