Adult body has a pattern of white, black, and brownish-yellow spots. Full-grown larvae have a series of light- and dark-brown transverse stripes. At the posterior end of late-stage larvae, there are tufts of setae.
Development. Eggs are deposited on larval food; hatching is in 18 days. Larval development takes 222 to 323 days, and includes 5 to 16 instars depending on conditions and the food material. Development is completed in one year. Household infestations produce adults in fall.
Habits. This species feeds on stored food materials and grain products, and also on dead insects in light fixtures.