ENTFACT-629: Grain Mites  |  Download PDF

by Lee Townsend, Extension Entomologist
University of Kentucky College of Agriculture 

Grain mites are pests that can feed on a variety of processed or finely ground grains, wheat germ, yeast, cheese, powdered milk, flour, or mold spores. Under hot, humid conditions, very large populations of these tiny creatures can develop rapidly. Female grain mites lay up to 800 eggs on the surface of food materials. 

The life cycle from egg to adult takes only about two weeks at normal room temperatures. Overcrowding in heavily infested products will force mites to move off in search of other food sources. This "spill over" can produce a fine dust-like layer of these mites on a shelf, product bag, or counter. This "mite dust" is often the first sign of trouble and usually means there are one or more heavily infested items not far away. 

There are no good chemical solutions to this problem. A thorough search must be made to locate infested packages so that they can be thrown away. All of the items on the shelf should be wiped off to remove and kill wandering mites before they enter another container. A rag with hot soapy water can be used to wipe up and clean out the mites on flat surfaces. Wash out the rag frequently and keep it soapy. 

Cracks and crevices on counters or in shelving can be cleaned with the crevice tool of a vacuum cleaner to remove both mites and fine particles of processed foods that can keep the infestation going. Immature stages of these mites can enter a resting stage that will allow them to survive for several weeks when conditions are not favorable. Thorough sanitation will help to remove as many of these as possible. In spite of the most thorough cleanup, some mites will remain behind. That is why it is important to be sure that all remaining potential food sources should be stored in tightly sealed containers that will keep wandering mites out. 

A thorough cleanup and sealing of stored products, along with ventilation to reduce the humidity, will bring the problem under control without the potential hazard of contaminating food or preparation surfaces with an insecticide. 

In general, applications of insecticides are not recommended in the kitchen or storage area. Prevention is the best cure. Do not buy items in damaged packages or containers that appear to be damp. Store potential problem items in sealed containers so that if an infestation develops, it cannot spread. Inspect storage areas regularly and use up old products before opening new ones. Keep the area well-ventilated and the humidity as low as practical. 

Revised: 10/95 

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. 

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE! 

Images: University of Kentucky Entomology