Yellow Mealworms

Facts, Identification & Control

Scientific Name

Tenebrio molitor


Yellow mealworm adults look like typical beetles, and are not worm-like in appearance as their common name suggests. They are dark in color, have a hard shell and are about ½ inch long. The common name mealworm comes from the appearance of the larvae (caterpillars), which are cylinder-shaped and about an inch long when full grown. Their coloration is yellow with brownish rings on the body segments. The larval body turns progressively harder as they grow.

Behavior, Diet & Habits

Mealworms go through an egg, larval, pupal and adult stages (complete metamorphosis) and their life cycle usually is completed in about three to six months. Adults only live about 30-70 days, depending on the temperature and suitability of their habitat.

Mealworms are categorized as secondary stored product pest. This means they primarily feed on materials that are damp, decomposing and moldy. Their preferred food sources are items such as leaves, dead insects, animal wastes and moist stored grains or grain products that are in the process of decaying.

Their normal habitat is dark, cool and moist locations where there is suitable food and sheltered areas such as under rocks, logs, in animal waste accumulations and in moist, stored grain storage areas.

More Information

Mealworms are seldom a serious problem in homes, so the steps to resolve mealworm problems are relatively simple and straightforward. First, inspect for and locate the source of the infestation, making sure to check for old, moist and decomposing materials. Once the source is found, use a vacuum to remove the food source and any insects you find. Using cleaners or insecticides are usually unnecessary. However, if products are needed to eliminate the problem, be sure to contact your pest management professional who has the expertise to correctly resolve mealworm problems.

The rearing and sale of mature mealworms is an important industry that supplies bait for fishermen, as well as food for pets.