There may be a variety of insects that show up, but in general, we lump them together as pantry pests. In nearly all cases, the adult flies while the larvae are worm-like. The more common ones are the Indian Meal Moth and the two versions of Flour Grain Beetles. While they have slightly different life cycles, generally eggs hatch in any kind a product that contains flour where the larvae stage feeds until it is time to transform into an adult.
The key to preventing these pantry pests is not to have any leftover flour that is going to get worked to the back of the shelf in the cupboards and pantries. It is better to use it up in cooking and baking than attempt to store it. If the flour is to be kept, store it in a very tight sealing plastic container or keep it in the refrigerator, or even better, the freezer.
If you do find some of that stored flour to be contaminated in your pantry, then it is a matter of disposing of just one container. Storing flour in the refrigerator dramatically slows the potential of contaminated product and if left in a freezer to zero or below, there will no chance of anything going wrong.
Flour products are not the only way pantry pests can make it into your home. Did you buy a dried flower arrangement or make one that contained flower seed heads from your own flower beds? Other potential sources include any of our dry pet foods that contain flour as an ingredient. Buy just enough to last a month to prevent the time needed for any pantry pests to show up. One of our favorite winter past times is to feed and watch the birds. If you do buy birdseed in large amounts, be sure to store it in an unheated area, like the garage, and in a tight-sealing container, just as you should the flour in the pantry. The same goes for the food for other four-legged pets like gerbils, mice and rabbits.
In a future column, I will be covering what to do if you discover you have pantry pests. In the meantime, do all you can to prevent them from getting established in your cupboards and pantries.
Richard Hentschel is a Horticulture Extension Educator with University of Illinois Extension, serving DuPage, Kane and Kendall counties. Stay tuned to more garden and yard updates with "Down the Garden Path" at go.illinois.edu/downthegardenpath and the "Green Side Up" podcast at web.extension.illinois.edu/podcasts/greensideup