The merchant grain beetle and sawtooth grain beetle (Oryzaephilus mercator and Oryzaiphilus surinamensis) are some of the most commonly encountered kitchen pests in Edmonton. 

The beetles are flightless, slender-looking, dark brown insects measuring only 3 mm (an eighth of an inch) long. The sawtooth grain beetle has characteristic “teeth” running down the sides of its prothorax, but is otherwise almost identical to the merchant grain beetle.

Worm-like larval stages are most often found in infested food packages while the very active adult beetles may escape and spread to other dry foods, or infest small cracks in the woodwork, feeding on any available spilled food materials.

The Problem

These insects are often brought into the home through infested food purchases, including grains, cereal and pasta. They can render food inedible, or reduce the desirability of food with their presence.  They prefer processed grains like cereal, oatmeal, rice, or flour, but can also infest chocolate, nuts, dried fruit, and even spices or tobacco.

What You Can Do

Eliminating such pest problems is achieved through good food storage (use glass, heavy plastic or metal containers with tight-fitting lids) and house cleaning practices. Keep food storage areas clean and sanitary.  Wipe up food spills immediately.  A crack and crevice vacuum tool is useful for removing food and insects from cupboard joint lines as well as the bottom edge of kitchen baseboards. Remember to dispose of the vacuum bag contents which may contain live insects.

Infested crack lines can then be injected with diatomaceous earth, a low-toxicity insecticide dust that will provide effective, long-lasting insect control if applied according to label direction. Diatomaceous earth is available through seed stores, garden centres and other insecticide retail outlets.

Application of stronger pesticides, such as permethrin sprays is not recommended.