Pest Guides

Warehouse Beetle

Trogoderma variable

Appearance

Warehouse Beetle Image
  • 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.

Lifecycle

  • 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.

Habits

  • 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.

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