Weevil Basics

While granary and rice weevils do not bite, sting, spread disease or damage structures, they damage your food. Brought into your home typically in the egg stage, these tiny insects, measure about 1/8 inch long as full-grown adults. Once in the larval and adult stages, they feed on the internal portions of most whole grains. Infestation can quickly become evident once the pupa or adult stage is reached and the weevil's telltale snout is present. Rice weevils are flying insects, but granary weevils, which feed on whole-grain flour, are nonflying insects.

Stopping an Infestation

With females laying up to about 250 eggs throughout their life span, it is important to stop an infestation before it gets under way. Prevent eggs from hatching by microwaving whole-wheat flour and all other grains brought into your home for 5 minutes with your microwave set to high. Do this in a shallow, microwave-safe dish, and then allow the flour to rest and cool for several minutes before handling it. Store the flour in an airtight container in a cool, dark location.

Weevil Prevention Tips

In warmer months, you are more likely to get a weevil infestation, especially when storing grains in excess of one month. Purchase smaller quantities of grains for quicker use, and always store grains in insect-resistant containers, such as glass, plastic or metal ones with airtight lids. For storage of grains beyond one month, refrigerate or freeze them to prevent an infestation. Always inspect grains thoroughly before purchase for signs of infestation, such as larval-stage weevils.

No-Microwave Method

If you don't own a microwave, you can still get rid of weevils in your whole grains by heating wheat flour and other grains in your oven set to 130 degrees Fahrenheit for 30 minutes. Alternatively, you can freeze your flour, cornmeal, rice and other grains in a 0 F freezer for four days to kill weevil eggs and larvae. Once either process is completed, store all whole grains in a well-ventilated area in airtight containers.