The lesser grain borer (Rhyzopertha dominica) is a destructive stored-grain pest that attacks wheat, corn, rice, barley, and other grain products in Arizona homes and commercial storage facilities. Adults are small (2–3mm), dark brown to black, cylindrical beetles with a distinctive hooded appearance — the head is bent downward and hidden under the thorax when viewed from above. Both adults and larvae bore into grain kernels, consuming them from within and leaving behind a fine powder and a distinctive honey-like or musty odor that is one of the most reliable signs of infestation. Adults can fly, which allows them to spread between grain storage areas.

Controlling lesser grain borers in Arizona requires discarding all infested grain products and thoroughly cleaning storage areas. Inspect all whole grain products — wheat berries, whole corn, rice, and barley are the most common targets. Look for adult beetles, fine powder (frass), and the characteristic musty odor. Discard infested products in sealed bags outside the home. Vacuum storage areas thoroughly and wipe with a food-safe cleaner. Store all grain products in airtight glass or hard plastic containers. Freezing grain for 72 hours before storage kills any eggs or larvae present.

Lesser grain borers thrive in Arizona's warm, dry climate and are one of the most common grain pests in the state. They are particularly problematic in homes that store grain in bulk for long periods. If you find lesser grain borers in multiple storage areas or notice the characteristic musty odor in grain products, act immediately. Pest Control Bros LLC provides stored-product pest inspections and treatment throughout Maricopa, Chandler, Mesa, Tempe, Gilbert, and Casa Grande. Call (520) 424-5244.