Extension News

Did I Bake Beetles?


By Laura Jesse
Iowa State University Extension

It is a sight we all dread: opening the flour container, peering in and seeing little beetles all over the surface. Even for an avid bug lover such as myself there is just something unsettling about finding insects in my food. My first thoughts are always; When did I last use that flour? Would I have noticed if it was infested? Did I eat beetles?  I remind myself that there are plenty of insects ground up in flour and most food items, but there is just something extra yucky about eating whole, living insect.  

There are several insect pests commonly found in kitchens eating our food. You know, I sometimes wonder if the insects worry about the human pests that keep coming into the kitchen to eat their food. Probably not. The insects are likely just grateful we go to the grocery store and bring back more food for them; insects can’t drive very well. 

The confused flour beetle and red flour beetle are very similar species. Both beetles are small, about one-fourth inch, and brown. Both the adults and larvae feed on a variety of grain based products, particularly, cereal products such as flour, cake mix, cornmeal, crackers, dry pet food and so forth. Other frequently-infested items are chocolate, nuts and seeds (such as bird seed). Both adults and small, off-white larvae will be found in an infested food item. The adult beetles often wander away from the infested material and will be found inside cupboards or anywhere in the house.

Cigarette and drugstore beetles are two closely related species of small, reddish brown beetles that are moderately common pests in kitchens. The cigarette beetle was at one time a very important pest of the tobacco industry and got its name from the damage it did to stored tobacco. The drugstore beetle gained its name because it was frequently found feeding on drugs in pharmacies many years ago. For both insects an infested item will contain the one-eighth inch long, reddish brown, oval beetles and small, white larvae. Adult beetles often wander away from infested materials and may be found throughout the kitchen or house.

I have also received samples of cigarette beetles found in rice, dried potatoes, paprika, raisins, grain-based mouse bait, dried straw flowers and a table centerpiece made of varnished bread. Drugstore beetles are known to feed on leather, wool, hair, books and drugs.

Control of any stored food pest requires locating and eliminating infested item(s). All potentially infested foods should be checked. The insects may be in unopened boxes or containers. Think of this as a good excuse to clean out the cupboards and bake all those old cake mixes. When you find infested items they can be thrown away or the insects killed by freezing the item for one week or heating it in a 140 degree oven for 15 minutes.  

Once you have emptied the cupboards, thoroughly vacuum clean the shelves holding infested items, paying particular attention to cracks and corners. Vacuum cleaning picks up hiding insects and spilled or infested material.  Empty the vacuum cleaner or discard the vacuum cleaner bag after use to prevent reinfestation.

Insecticide sprays are not recommended for controlling insects in stored food cupboards.  Washing shelves with detergent, bleach, ammonia or disinfectants will not have any effect on insect pests.

As a precaution against reinfestation, you may want to store susceptible foods in sealable glass, metal or heavy plastic containers or in the refrigerator or freezer until you are convinced the insects have moved on to greener pastures.


Contacts :
Laura Jesse, Plant Pathology, lrahnsen@iastate.edu, (515) 294-0589

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu