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Just Wait Out Foreign Grain Beetles

Jeffrey Hahn, Extension Educator

Jeff Hahn, Univ. of MN Extension

Photo 1: Don't confuse tiny foreign grain beetles for flies or fleas

Very small, brownish beetles are being found in some buildings, especially homes that have been recently constructed. Proper identification is critical as these beetles may be confused for other insects, such as fruit flies, drain flies, or fleas. A foreign grain beetle is about 1/12th inch long and reddish brown with a flattened body.

Foreign grain beetles can also fly which is why they might be confused for small-sized flies. However, foreign grain beetles have a generally harder body compared to the softer bodied flies. Fleas also have a relatively hard body but are fattened instead from to side to side; fleas are also wingless and can't fly.

The favorite food of foreign grain beetles is fungi and so they are typically found in relatively damp areas. They are often associated with new construction because the moisture in wall voids when construction is first completed in conducive for fungi which then provides a food source for the foreign grain beetles. Despite their name, foreign grain beetles are not typically found infesting food products in homes. They prefer to attack old, moldy grain products.

Fortunately foreign grain beetles are only a temporary nuisance. Adult beetles are active during late summer and early fall and then go away on their own. The beetles will survive only for one or two years in a home before it becomes too dry to support fungi and the beetles. Tolerate foreign grain beetles until they go away on their own. The best control is physical removal, e.g. with a vacuum. Insecticides do not prevent foreign grain beetles from appearing and their use is not recommended.

Click here for more information on foreign grain beetles.
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