Lesser mealworm
Alphitobius diaperinus (Panzer)


Secondary pest: grain feeder
Order: Coleoptera
Family: Tenebrionidae
Acronym: ADI


  • Adults are dark reddish brown to black and 5.5 to 7.0 mm in length.
  • Eye is less deeply incised: only 2 to 3 facets, in A. diaperinus; only 1 facet wide in A. laevigatus (black fungus beetle).
  • Larvae are yellow brown in colour and cylindrical in shape reaching a length of 15 mm at maturity.

Similar species

Commodities affected

  • Feeds on broken grains of wheat, barley, cowpeas, rice, corn
  • Will also feed on fungus, is scavenger on animal protein

Signs of infestation

  • Disagreeable odour in the commodity is an early indication.


  • Damage is not distinctive

How to control

Geographic range

  • Is distributed worldwide and found across Canada

Where found

  • Prefers grain, cereal products and animal food that are damp and mouldy
  • Is not harmful to grain that is sound and dry
  • Is a known pest of poultry houses (in chicken droppings)
  • Larvae can transmit poultry diseases
  • Will also burrow into insulation panels in poultry houses
  • Presence indicates conditions favourable for more serious pests
  • Is unlikely to survive winters outdoors

Life history

  • Adults are relatively long-lived (400 days) and can fly.
  • Females lay eggs in clumps amongst the food.
  • Larvae move actively amongst the food source.


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