Flour beetles, also referred to as flour weevils, are beetles that commonly lay their eggs in flour, rice, and other milled grains. They are tiny insects, averaging only .125 of an inch (3.17 mm) in length. These bugs are thick bodied and brownish red in color, and are one of the most frequent pests that plague household cupboards.
Female flour beetles usually lay more than 500 eggs during their life cycle, which usually lasts about a year. The eggs hatch into larvae that resemble tiny whitish gray worms. It takes a couple of months for the larvae to become adult beetles.
Though many types of beetles have been known to infest grain products, two species in particular are the most commonly found in household cupboards. These are the flour beetle and the red flour beetle. These two types of flour beetles are almost identical except for the shape of their antennae. The flour beetle has antennae that curve inward toward each other, while the red flour beetle’s antennae have very little curvature at all.
Many people believe that a flour beetle infestation is caused by unsanitary conditions, however, this is often not the case. In many instances, products purchased at groceries are already contaminated with weevils before they are even opened. Contamination of grains can occur in any stage of the milling process, and even if flour beetles are found during processing, it is often near impossible to get rid of the eggs. This is because the eggs are so miniscule they cannot easily be distinguished from the grains.
There are some obvious ways to help ensure that grains purchased at grocery stores do not contain flour beetles. Shoppers should avoid purchasing products with packaging that is torn or damaged. If the glued tabs on the edges of boxes seem loose, these packages should also be avoided. It may also be a good idea to check the "sell by" date on the packages. The longer a package stays on shelves, the more likely it is to become infested with pests.
Once milled products are purchased, home storage can play an important role in keeping the grains safe from beetle infestation. Flours or grains that come in paper bags should be put into containers that can be sealed. This includes containers made of glass or tin, as long as they have openings that can be tightly sealed against pests. Many people prefer the use of plastic vacuum type seals, as they also help preserve food freshness while protecting the foods from infestation.