Hairy spider beetle
Ptinus villiger (Reitter)


Secondary pest: Grain feeder
Order: Coleoptera
Family: Anobiidae
Acronym: PTI


  • Adults can be separated from other species by examination of the setae on the elytra: On P. villiger the setae on the elytral intervals are unequal in length, some setae on the third, fifth and seventh intervals are approximately twice as long as those on the remaining intervals.
  • Larvae are grub-like and white in colour.

Similar species

Commodities affected

  • Affect flour, corn meal, rolled oats, bran, feeds
  • Will feed on stored grain at the surface (wheat and rye)

Signs of infestation

  • Presence of webbed granular material
  • Irregular damage (chewed holes) to endosperm


  • Damage results from accumulation of silk and granular material

How to control

Geographic range

  • Is found worldwide and across Canada
  • Is one of the most common spider beetles in Canada

Where found

  • Can be a serious pest of cereal products, especially damp grain
  • May be a pest of animal feeds in the prairie provinces
  • Is found primarily in mills, empty granaries and warehouses where bagged flour is stored
  • May also be found in homes

Life history

  • Females lay eggs in cracks and crevices around the food supply.
  • Larvae may be somewhat gregarious and form feeding clusters of 3 to 4 individuals amongst several kernels glued together.
  • Larvae secrete a silky substance to form a puparia.
  • Adults are tolerant of lower temperatures, fly readily and are active in dim light.


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