Minimum Life Cycle: One year.
Distribution: Cosmopolitan in the United States.
Eggs - Laid in grain or food products.
Larvae - Feed in grain.
Adults - Feed in grain.
Yellow and Dark Mealworm (Tenebrio molitor). The yellow and dark mealworms are not considered serious pests because of their long life cycle (usually one year). The mealworm larvae and adult beetles both feed on whole grain and grain products. The eggs are sticky and are deposited in the loose food particles. The larvae are active crawlers and the adults are good fliers. The adults have aggregation pheromones and usually prefer dark areas (Figure 16).
(Slide and top caption from USDA ARS Agric. Handbook No. 500.)