Adult: 1/8” long and oblong in shape. Brownish black with yellowish markings. Have markings on their elytra (wing covers). Short antennae.
Larvae: 1/4” long. Yellowish white and brown. Covered in long hairs and barbs.
Developmental time is 32-43 days.
Females lay up to 94 eggs which, at 90°F/ 32°C, hatch in 6 days.
There are normally 6 larval instars, but mature larvae can diapause. The percentage that diapause increases from 32% to 67% when exposed to room temperature daily and this increases to 80% when handled/disturbed daily along with room temperature storage.
Diapausing larvae may delay pupation for as long as 2 years. If a larva does not diapause, it requires approximately 34 days to pupate.
Males generally pupate after one less molt than females. Pupation generally occurs near the surface of the food.
The larval skin splits but is not cast off. Pupal development occurs within this split skin and requires 4 days. Adults will remain in the last larval skin for up to 7 days and mate shortly after emergence. Maximum adult longevity is 100 days.
This insect is very cold tolerant. Adult survival is also high at low temperatures.
Adults are good flyers.
Are found in over 90 different types of foods including: cake mix, cereal, cookies, corn meal, dog food, pasta, oats, and grains.
Larvae live in dark places and prefer to eat high protein foods like seeds and nuts.
They cannot feed on whole grain, but can feed on broken kernels that are usually present.