UMCE Pest Management

Pest Management Office  491 College Avenue  Orono, ME 04473-1295
(207) 581-3880  1-800-287-0279 (in Maine)  Fax (207) 581-3881
 


Flour beetle larva and adult

Flour Beetles

Flour Beetle Larva and Adult

 

Description & Biology

Common flour beetles found in Maine include the confused flour beetle and the red flour beetle. They are similar in habits and appearance. Both beetles primarily infest flour and, to a small extent, foods made of processed grains. Confused flour beetles and red flour beetles are often found together. Even though they cannot attack whole grains, there are usually enough broken kernels and grain dust, caused by the rubbing of grain during handling, for these beetles to survive. Any home can be invaded by these beetles through the transportation and storage of grains or grain products such as cereals, macaroni, flour, etc.

Flour beetles are not known to carry or spread any diseases that affect humans. Nor do they attack anything other than grain or starch foods (at least not for long). However, in search of their favorite foods, they may become an annoyance, invading all areas of a home.

The beetles (adults) are shiny, flattened, reddish brown insects about 1/7" long, and very active. The larvae are brownish to yellowish white, worm-like insects with three pairs of legs. They are about 1/16" when fully grown.

Both beetles can live up to three years. Unlikely to survive Maine’s winter temperatures, they seek protection in heated areas or areas where high moisture grain is heating. Generally, these insects are considered weak fliers, but warm temperatures make them more active and, with the help of a wind, they can apparently move long distances.

Management

Sanitation

Emptying and cleaning food containers before replenishing supplies and checking foods stored for long periods are the most effective means of keeping flour beetles out of your kitchen. Plastic, glass, or metal containers with tight fitting lids are also helpful.

Never discard foods infested with flour beetles. You may give it the 125-140°F heat treatment in an oven for 30 to 45 minutes to kill all stages of development. Placing the infested food in a freezer for five days at 0°F should also kill the pests. Otherwise, the infestation may spread. A vacuum cleaner is an excellent aid, but the bag should be sealed before disposing.

Insecticides

An area spray containing pyrethrins plus piperonyl butoxide may be used to spray all areas in a kitchen but must be kept off food and dishes and utensils. Any other household spray must also be used according to directions but only in cracks, crevices, corners, and under or behind things where insects are likely to hide. Consider a household formulation of malathion (deodorized) for a somewhat longer residual action. Either malathion or carbaryl (Sevin) should help keep beetles out of your home. Apply one of these products in a 25-foot band on the lawn around the house. Also be sure to spray the area where the wood or siding and foundation meet.

 

When Using Pesticides
 ALWAYS FOLLOW 
LABEL DIRECTIONS!

James F. Dill, Pest Management Specialist
Clay A. Kirby, Insect Diagnostician
2004

Where trade names are used, no discrimination  is intended and no endorsement by Cooperative 
Extension is implied.


PEST MANAGEMENT OFFICE | UMCE HOMEPAGE | UMAINE


Pest Management Office Last Modified: 10/31/07
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