Flour mill beetle

Cryptolestes turcicus (Grouvelle)


Primary pest; grain feeder
Order: Coleoptera
Family: Laemophloeidae
Acronym: CTU


  • Flour mill beetle is often confused with the flat grain beetle (Cryptolestes pusillus).
  • Adults are small (1.5 to 2.0 mm), reddish brown and flattened with long bead-like antennae.
  • Adults have a ridge (sublateral carina) on the head and prothorax.
  • Larvae are elongate and flattened with well developed legs.
  • Larvae are pale, white to yellow in colour with a darkened head capsule and dark urogomphi present.
  • Larvae move actively amongst the food feeding on the endosperm or germ.


Similar species

Commodities affected

  • Flour, damaged grain
  • Waste grain, cacao, spices, dried fruit, copra

Signs of infestation

  • Damage is not readily identifiable as being caused by this species.


  • Damage is usually restricted to grain stored under high moisture conditions.
  • Both larvae and adults feed on germ and endosperm.
  • Heavy infestations may cause grain to heat and spoil.
  • Flour mill beetle may spread fungal spores through grain.

How to control

Geographic range

  • Is found in Europe, North Africa, Japan, some South American countries and North America
  • Is found across Canada

Where found

  • Can survive Canadian winters only in heated structures
  • Is found mainly in machinery of flour and feed mills, occasionally in grain elevators and warehouses
  • Requires high temperature and relative humidity for optimal development but is cold tolerant

Life history

  • Beetle’s development is favored by the presence of fungi in its diet.
  • Females lay eggs in crevices or loosely amongst the food.
  • Adults cannot climb up glass.

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