Iowa Insect Information Notes

Mealworms

Mealworms

The mealworms are common, widespread insects that occasionally infest stored products. The larvae are elongate and cylindrical ("worm-like"), hard-bodied and yellow to golden brown in color. The mealworm adults are nocturnal, black, hardshelled beetles about one inch long. Mealworm adults and larvae are usually found in moist, dark, undisturbed places. Typical habitats include accumulations of stored grain, damp or damaged grain residues, or stored grain products. They may also be found in accumulations of moist organic matter.

When mealworms are found indoors, control requires locating and eliminating the source of the infestation. This may require thorough investigation since larvae and adults may crawl considerable distances from the source of the infestation, and these wanderers do not necessarily indicate the areas which are necessary to treat. Cupboards or shelves holding infested items should be emptied and thoroughly vacuum cleaned. A light spray of household insecticide can be applied according to label directions to cracks and corners of infested storage areas. If shelves are treated, food products should not be replaced until the insecticide is completely dry and fresh shelf paper has been installed. For more information on insecticides please see "Insecticides for Indoor Use." Mealworms may live in long-forgotten grain accumulations such as stored garden seeds, grain-based mouse bait and bird seed.

Updated 07/14/2005 - 2:04pm