Merchant Grain Beetle

Both merchant grain beetles and their close relatives, the sawtoothed grain beetles (Oryzaephilus surinamensis) are common stored-food product pests that infest cereals, corn meal, cornstarch, popcorn, rice, dried fruits, breakfast foods, flour, biscuit mix, rolled oats, bran, macaroni, sugar, drugs, spices, herbs, candy, dried meats, chocolate, bread, nuts, crackers, raisins, dried dog and cat food, and other foodstuffs, rendering them unusable.

The beetles are capable of chewing into tightly sealed packages, including unopened paper and cardboard boxes and cellophane, plastic, and foil wrappings. They do not bite or sting, spread disease, or damage structures or furniture.

Adults of both species are flattened, reddish-brown beetles around a tenth of an i... read morench long. They have six sawtooth-like projections on each side of the prothorax (the middle part of the body, between the head and the wing covers), and the wing covers (elytra) are longitudinally grooved. Under magnification, the sawtoothed grain beetle is seen to have a temple area (the region behind the eye) about half as long as the eye. The temple area of the merchant grain beetle is much smaller.

The merchant grain beetle can fly, but the sawtoothed grain beetle cannot.

The merchant grain beetle prefers nuts, seeds, and dried fruit. The sawtoothed grain beetle prefers cereal-based products, feeding on finely divided food particles, rather than whole grains.