The Grain Weevil

Home Pest Control News The Grain Weevil
grain-weevil-up-close-Owl Pest Control Ireland

The Grain Weevil – Sitophilus granarius


The adult weevil are small (2.5-4mm) and brown. They are very noticeable with their long snout and elbowed antennae. The elytra are unmarked and the chest has oval punctures. It cannot fly as the wings are too small.

Life cycle:

The Grain Weevil is triving in high humidity and temperatures (optimum temperature is 30 º C). They live for about one year. Under ideal conditions the development from egg to adult takes 25 days, but on average it takes around 2 months.

Larvae develop hidden inside the grain. Usually there is no external sign of infestation until after about a month when the grown weevil chews through the seed shell to get out. Females lay eggs after 2 weeks and in total this represent 150 to 300 eggs.

Commodities infested:

As the name indicates the Grain Weevil is a very common pest in stored grain. In Northern Ireland a survey showed that 12% of local farms were affected. The weevil is usually found in wheat, barley, rye, oats, corn, and also rice. It can also be found in pasta and flour. In houses infestations usually arise from bird seeds.

If you notice grain weevil activity in your house you should inspect your food presses immediately and discard the damaged items.