Yellow Mealworm Beetle (Tenebrio molitor)
The beetles are robust, black and nearly 18mm long, resembling many ground beetles in size, shape and colour. The larvae are distinct, being honey yellow in colour with a smooth, highly polished, hard, cylindrical (wormlike) body about 3mm thick and up to 28mm long at maturity.
Adult beetles are attracted to night-lights, are strong fliers, and are found in dark places. Each female lays about 275 eggs, which hatch into larvae in 4 to 14 days. Eggs are laid singly or in clusters during the spring over a period of 22 to 137 days. Larvae may spend up to two years in this stage depending on the environment. Individual larvae may wander far from the food source to pupate, making it difficult for homeowners to locate the source of infestation.
Common sources are cornmeal, flour, cake mixes, cereals, meat scraps, dead insects, bran, litter from chicken houses and birds’ nests.
To control these pests, the infested area should be thoroughly cleaned to remove the debris on which the larvae fed (bird nests, food etc). Application of a broad spectrum residual insecticide will then normally control the problem.