Foreign Grain Beetles

Facts, Identification & Control

Latin Name

Ahasverus advena (Waltl)


The foreign grain beetle, Ahasverus advena (Waltl), may have gotten its name by being a pest in grain storage facilities. It is a small insect. The adults range in size from 2 to 3 mm. They are reddish brown in color. When viewed from above, the shell behind the head has rounded projections on the front corners. These projections may be easier to see with a magnifying glass.

Behavior, Diet & Habits

The foreign grain beetle is a scavenger. It feeds on fungus, moldy grain and dead insects.

The foreign grain beetle is also a pest in homes and businesses where moisture problems cause fungus to grow. When these beetles are present, it can be an indication that there is a moisture problem in the building.


The female beetle lays eggs on food material. In a warm, humid environment, the life cycle, from egg to adult, takes about three weeks.

Signs of a Foreign Grain Beetle Infestation


Sometimes new homes get wet during construction. The water enables mildew or mold to grow. Foreign grain beetles can invade to eat the mold during construction. Infestations in new homes often start inside wall voids. The homeowners become aware of the problem when the beetles begin to come out from under the baseboards. In many of these situations, when the wood and sheetrock dry out, the fungus dies and so do the beetles.

There have also been reports of these beetles in older buildings. They invade where leaks, floods or other moisture problems have caused fungus to grow. Foreign grain beetles are good fliers. They can enter through windows.  A humid bathroom can provide a suitable environment for these beetles to thrive.

More Information

Controlling foreign grain beetles begins with a thorough inspection. Throw away any food that the beetles have infested. Eliminate any moisture problems. This will eliminate any mold or fungus that the beetles might have been eating.

In some situations, insecticide may be necessary. Dust insecticide is effective inside wall voids. Liquid or dust insecticide can be effective in the cracks and crevices beneath baseboards. It is advisable to call pest control professionals. They will have the products and equipment necessary to control foreign grain beetles effectively.