Beetles Identification Guide

Distribution: Throughout most of the temperate regions and known to survive
for a considerable time when introduced in the tropics, though incapable
of breeding there. In Canada the species is found from Nova Scotia west
to British Columbia.
Economic importance: Adults and larvae feed on a wide variety of materials of
both animal and vegetable origin but have a preference for moist and decaying
grain and cereal products. In Canada, they are found most frequently in granaries,
grain elevators, mills, bakeries, and food stores. As is true for other storedproduct
pests, the damage done by this species is not due mainly to its feeding
habits but largely to the presence of excrement and exuviae, which reduce the
commercial value of the food. In Britain members of this species are common
inhabitants of bird nests, especially those of pigeons.
Tenebrio obscurus Fabricius
dark mealworm
ténébrion obscur
Diagnosis: The species differs from T. molitor in having the punctation on the
clypeus, frons, and pronotum denser, the elytra somewhat pear-shaped, and the
body dull.
Sexual dimorphism: Males have the ventral angle of the fore tibia extended into
a small process; females have the ventral angle rounded (Fig. 259).
Distribution: Throughout most of the temperate regions. In Canada the
species probably occurs from coast to coast but has not yet been reported
in Nova Scotia, New Brunswick, Manitoba, or Saskatchewan.
Economic importance: Like T. molitor, this species feeds on materials of both
animal and vegetable origin. In Canada it is most commonly reported in the
litter of chicken coops, birdhouses, and stables.
Tribolium audax Halstead
American black flour beetle
Diagnosis: The species is distinguished from the other Tribolium included here,
except T. madens, in having the body dark brown to black with the eye about 4
facets wide laterally. Members of T. audax differ from those of T. madens generally
by their smaller size and more elongate body shape, the denser punctation
on the frons, the smaller eyes, the less transverse and less convex pronotum, the
presence of a slight depression on the prosternum in front of the intercoxal process,
and the lack of a setiferous patch on the male fore femur. In addition, the
width of the head across the eyes is subequal to that in front of the eyes.
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