Foreign Grain Beetles

Facts, Identification, & Control

Latin Name

Ahasverus advena (Waltl)


What Do They Look Like?

flour beetle

  • Color: They are reddish brown in color.
  • Size: The adults range in size from 2 to 3 mm.
  • Characteristics: 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.

How Did I Get Foreign Grain Beetles?

Infestations in new homes often start inside wall voids. They later emerge from baseboards and ceiling fixtures into living spaces. These pests may also enter through windows.

How Serious Are Foreign Grain Beetles?

Typically, foreign grain beetles are no more than nuisances in homes. While these pests may fly around in large numbers and annoy residents, they do not bite humans. These insects do not harm wood, furniture, or fresh pantry goods.

Signs of an Infestation


Foreign grain beetles often move into old water-damaged houses or new homes during construction to eat mildew. They invade where leaks, floods, or other moisture problems have caused fungus to grow. Since these beetles feed on mold and fungi, they often appear in homes that were built with waterlogged or improperly seasoned wood. In many of these situations, when the wood and sheetrock dry out, both the fungus and beetles die.

How Do I Get Rid of Foreign Grain Beetles?

What You Can Do

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

What Orkin Does

Your local Orkin technician is trained to help manage foreign grain beetles and similar pests. Since every building or home is different, your Orkin technician will design a unique program for your situation.

In some situations, insecticide may be necessary. Liquid or dust insecticide can be effective in cracks and crevices beneath baseboards, while dust insecticide is effective inside wall voids.

Orkin can provide the right solution to keep foreign grain beetles in their place and out of your home or business.

Behavior, Diet, & Habits

Where Do They Live?

While foreign grain beetles are known to infest grain storage facilities, they commonly inhabit a variety of places such as:

  • Damp walls
  • Forgotten food packages
  • Humid bathrooms
What Do They Eat?

The foreign grain beetle is a scavenger, with a typical diet consisting of:

  • Dead insects
  • Fungus
  • Moldy grain

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