Skip to main content

Foreign Grain Beetles in New Construction

Elongate, reddish-brown beetle on a white background.
Figure 1. Foreign grain beetle. Note the knobs on the thorax (the segment behind the head). Courtesy: Amanda Bachmann

Even though fall is here, insects are still active, especially those that spend time indoors. We’ve received pictures and samples from across the state of small, reddish-brown beetles that appear inside homes. These insects are the foreign grain beetle. Their name implies that they are a pest of grain; however, they actually feed on the mold and fungi associated with stored grain. The foreign grain beetle samples we receive most frequently come from newly constructed homes rather than grain bins.

Foreign grain beetles look very similar to other common stored grain pests (elongate and reddish-brown), but they are about half the size at barely 1/8 of an inch long. Unfortunately, their most distinguishing characteristic (knobs on the front corners of their thorax) is only visible under magnification (Figure 1).

The good news is that these beetle populations tend to disappear on their own. The adults that emerge from wall voids and other spaces inside new construction are generally unsuccessful at beginning another generation indoors. They can be managed like many of our other fall invaders by vacuuming or sweeping up the adults and disposing of them. No insecticide application is necessary.

Related Topics

Garden & Yard Issues