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Foreign Grain Beetles

An introduced species, commonly associated with grains, the foreign grain beetle is typically a minor pest from an economic stand point due to the fact that they infest moist deteriorating stored products.  This species is now found worldwide.  Adult foreign grain beetles are reddish brown in color with a flattened body, approximately 1/16th to 1/8th of an inch in length.  The back of the beetle has numerous small hairs or setae.  Wing covers have rows of pits.  Antennae are less than half the length of the beetle’s body.  Unlike the merchant and saw-toothed grain beetle, foreign grain beetles lack the saw-tooth like protrusions just behind their head.  Foreign grain beetles scavenge for their food, feeding on both plant and animal debris including fungi that grow on these materials.  Decaying or moldy grains attract these beetles. This beetle has also be found in newly built homes associated with mold growth on sheetrock due to the moisture from the plaster coats as well as in homes with water leaks resulting in moldy conditions.  Adults are strong fliers and are attracted to lights at night, making infestations possible without an introduced product such as decaying grain.

Females lay 1-3 eggs at a time approximately 2 days apart with a total of 100-300 in her lifetime.  Eggs hatch within a few days.  Larvae are yellowish white in color and when mature is up to 1/8th of an inch in length.  Like their relatives the merchant and saw-toothed grain beetles, foreign grain beetles larvae have 3-segmented antennae.  Eliminating a grain beetle infestation must include location and elimination of the food source (i.e. decaying grain, mold, or fungi).  In areas where moisture is a problem, leaks must be repaired and moisture reduced or eliminated.  Applications of residual pesticides, especially dusts, into wall void areas where mold or fungi were the food source will assist in eliminating the infestation.  In the case of decaying grains, products should be removed, the areas should be thoroughly sanitized and if needed, a residual pesticide applied by a pest control professional.