Red flour beetle

Tribolium castaneum (Herbst)


Primary pest (mills); grain feeder
Order: Coleoptera
Family: Tenebrionidae
Acronym: TCA


  • Adults are a small reddish brown beetle and are about 4 mm long.
  • Adults are easily confused with other Tribolium species.
  • Larvae are whitish with brown bands.
  • Larvae reach a length of 8 mm prior to pupation.


Similar species

Commodities affected

  • Stored grains, oilseeds
  • Starchy materials, beans, peas, spices, dried plant roots, fruit, yeast, chocolate
  • Consumes dead insects, herbarium specimens
  • Prefers damaged grain but will attack intact wheat kernels, feeding first on the germ and then the endosperm

Signs of infestation

  • Heated grain
  • Pinkish coloration to food products at very high population densities


  • Is a generalist feeder and damage is not readily attributable to this pest
  • Releases a noxious secretion, when disturbed, resulting in a pungent odor in the infested commodity, rendering milled products unfit for consumption
  • May cause food to acquire a pinkish tinge when a large number of insects are present
  • Is typically found in grain that has become heated

How to control

Geographic range

  • Is found across Canada
  • Survives Canadian winters in heated and protected places
  • Is distributed worldwide and is more common in warmer climates

Where found

  • Is found in grain bins, elevators, vessels, railcars, mills
  • Is occasionally found in retail stores and warehouses
  • May infest packaged food
  • Is capable of flight in warm weather
  • Is more common in grain stores than the confused flour beetle
  • Is one of the most common grain feeding insects found in grain stored on Canadian farms

Life history

  • Each female lays 400 to 500 eggs.
  • Breeding takes place in a temperature range of 22oC to 40oC.
  • Optimum development occurs in the range of 32oC to 35oC.
  • Red flour beetle has one of the highest rates of population growth for stored-product insects.


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