Beetles Identification Guide

Sexual dimorphism: Sexes are externally similar.
Distribution: Exclusively North American. In Canada the species ranges from
Quebec west to British Columbia.
Economic importance: In Canada T. audax is usually found, sometimes in large
numbers, in empty granaries, flour and feed mills, retail stores, warehouses, and
boxcars; the adults and larvae feed on cereals and their products. The species is
not as serious a pest as some of the other Tribolium species occurring in Canada.
Under natural conditions, it dwells under the bark of Pinus and in cells of the bee
Megachile rotundata (Fabricius).
Tribolium castaneum (Herbst)
red flour beetle
tribolium rouge de la farine
Diagnosis: The species is distinct from the other Tribolium dealt with here in
having the ventral part of the eye large, extended medially to the level of the
maxillary fossa. It is most similar in size and coloration to T. confusum but also
differs from it by the 3-segmented antennal club and the less deeply incised eye
(width 3 or 4 facets laterally).
Sexual dimorphism: Males have a setiferous patch on the posterior side of the
fore femur (Fig. 260). Females have no such setiferous patch.
Distribution: Cosmopolitan but more common in warmer regions of the world.
In Canada the species is found in the temperate regions, from Quebec west to
British Columbia.
Economic importance: This species is an important pest of stored grain, oilseeds,
and their derivatives. The adults and larvae feed on a wide variety of stored products.
They attack sound grain, particularly when the moisture content is high,
but prefer damaged grain. Although this beetle can probably survive winter conditions
only in heated places, its occurrence in Canada has increased in the past 5
years, and serious infestations have been reported in granaries, flour mills, and
feed mills throughout the Prairie Provinces. In Canada T. castaneum is the species
found most frequently in imported produce on cargo ships (Monro 1969).
Tribolium confusum Jacquelin du Val
confused flour beetle
tribolium brun de la farine
Diagnosis: The species is separated from the other Tribolium studied here by its
relatively small size (less than 4.5 mm) and the narrow eyes laterally (width of 1
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