Beetles Identification Guide

The species was recorded in Canadian cargo ships carrying oats, wheat, and flour
(Aitken 1975).
Ptinus villiger (Reitter)
hairy spider beetle
ptine velu
Diagnosis: Among the species of Ptinus discussed here, P. villiger is distinctive in
having the setae on the elytral intervals clearly unequal in length; some setae on
the third, fifth, and seventh intervals are about twice as long as those of the remaining
intervals. In the other Ptinus, the setae on the intervals are subequal in
size, or some setae on the third, fifth, and seventh intervals are slightly longer
than but less than twice as long as those of the remaining intervals.
Sexual dimorphism: Males (as in Fig. 224) have the elytra subparallel-sided, the
eyes slightly larger and more convex, the antennae longer (third segment twice as
long as the second), and the metasternum longer and convex in the posterior
half. Females (as in Fig. 225) have the elytra subobovate, the eyes slightly smaller
and less convex, the antennae shorter (third segment slightly longer than the second),
and the metasternum shorter and flat.
Distribution: Europe, Siberia, and introduced in North America, where it seems
to be restricted to the cold temperate regions. In Canada the species ranges
from coast to coast.
Economic importance: One of the most common ptinids in Canada and a serious
pest of cereal products, particularly damp grain, and of animal feeds in the
Prairie Provinces. The species is found mainly in mills, empty granaries, and warehouses
where bagged flour is stored.
Sphaericus gibboides (Boieldieu)
Diagnosis: The species differs from the other ptinids included here by the vestiture
on the dorsal surface. The pronotum and elytra are covered with grayish
testaceous scales with scattered, short setae slightly more golden; the scales and
setae on the elytra are narrower than those on the pronotum.
Sexual dimorphism: Sexes are externally similar.
Distribution: Mediterranean region and introduced in western North America
and New Zealand (Archibald and Chalmers 1983). In Canada the species is known
only in southwest British Columbia.
Economic importance: In Canada the species has only been reported infesting
165