Note: This is the first part of a two-part series on indoor pests. Read part 2 on drain flies and fungus gnats.
Finding pantry pests
While pantry pests generally show up in February and March, University of Illinois Extension is already getting emails and calls. If I am going to guess, this ahead-of-schedule appearance may be because we have been at home baking and cooking more in 2021, causing the cycle to start earlier.
Identification is a good place to start and from there, understanding the pest life cycle guides us through the removal process. The most common pantry pests are a moth and a couple kinds of grain beetles. One is easier to spot than the two others. The Indian meal moth adult will be seen flying around in the pantry or cupboard and circling light fixtures at night and windows during the day, while the beetles do not. The moth is often the one we see first, as the beetles do not leave their food source. Both the moth and the beetles have a complete life cycle – adult, egg, larva (worm), and pupa (cocoon). This plays into your removal and management of these pantry pests. Typically, these pantry pests establish themselves when unused grain products linger in the pantry. The flour used for baking cookies and pies after the holiday season makes its way to the rear of the shelf and there it stays.
What to do now
Once found, the first step is a very thorough cleaning of the pantry to remove any infected products. This is going to be any foodstuffs containing flour, regardless of being highly processed or not. Examples include cake, cupcake, corn bread, and pancake mixes; crackers; pasta products; oatmeal and any breakfast cereals. Literally anything that contains flour as an ingredient. Flour will no longer have that bright white color, being a grey with webbing in the bag or box. All those go in the garbage.
Those Indian meal moth larvae crawl away and pupate away from what they eat, so the next step is cleaning the pantry shelves, cracks, and crevices. Use the nozzle on the vacuum to get into those tight spots. If the shelves are movable, take them out, exposing webbed cocoons. Do not forget to vacuum the ceiling and wall corners. (Pro tip: Wait to put fresh shelf paper down until you know the pests are completely gone.)
Keep them away
Any foodstuffs left from the checking and cleaning process need be placed in tight sealing containers in case they were contaminated with eggs that had not hatched before your inspection. If later you find a product with a problem, you will only have to throw out that individual product, and you will not have to inspect the entire pantry again. You can place leftover flour in the refrigerator or freezer until used up.
Be vigilant over the next 4 to 6 weeks, looking for the flying Indian meal moth and their larvae along with the small grain beetles in the remaining products. It will not be uncommon to see the moths, but without a food source to lay their eggs, you will break the life cycle. In the future, buy flour-containing products in a quantity that will be used up in a month, not long enough for another outbreak to occur.
Read more on household nuisance pests here.
About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.