The merchant grain beetle (Oryzaephilus mercator) is a close relative of the sawtoothed grain beetle and one of the most common pantry pests in Arizona. Like its cousin, it has six saw-like teeth on each side of its thorax, but the merchant grain beetle can fly — a key difference that allows it to spread more readily through a home. Adults are tiny (2.5–3.5mm), flat, and fast-moving. They infest cereals, oatmeal, nuts, dried fruit, chocolate, and bird seed. Unlike many pantry beetles, merchant grain beetles prefer foods with a higher fat content, making nuts and chocolate particularly vulnerable. Both adults and larvae feed on food products.
Eliminating merchant grain beetles requires a complete pantry inspection and cleanout. Remove every item and check for live beetles, larvae, or the fine powder they leave behind. Pay particular attention to nuts, chocolate, and high-fat dried foods — these are the most common infestation sources. Discard infested products in sealed bags outside the home. Vacuum all shelf surfaces, cracks, and corners. Transfer all dry goods to airtight glass or hard plastic containers. Because merchant grain beetles can fly, check adjacent rooms and cabinets for adults. Pheromone traps can help monitor for re-infestation after cleanup.
Arizona's warm climate allows merchant grain beetles to reproduce year-round, with populations peaking in summer. The ability to fly makes them harder to contain than non-flying pantry beetles. If you find beetles in multiple pantry items or in rooms outside the kitchen, a professional inspection is recommended to locate all harborage sites. Pest Control Bros LLC provides pantry pest inspections and treatment throughout Maricopa, Chandler, Mesa, Tempe, Gilbert, and Casa Grande. Call (520) 424-5244 for a free inspection.
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