Beetles Identification Guide

few erect setae near the apex.
In the past, Mezium affine has been misidentified by some authors as M.
americanum Laporte de Castelnau, the American spider beetle. Adults of M.
affine differ from those of M. americanum in having the setal collar at the base of
the elytra continuous, whereas in the latter species, the collar is deeply interrupted
at, and on each side of, the middle. The American spider beetle does not
occur in Canada but is occasionally intercepted at ports of entry.
Sexual dimorphism: Sexes are externally similar.
Distribution: Europe, North Africa, and introduced in North America and New
Zealand. In Canada the species has been reported from Nova Scotia west to
Saskatchewan and in British Columbia.
Economic importance: In Canada the species has been collected occasionally in
warehouses and dwellings.
Niptus hololeucus (Faldermann)
golden spider beetle
niptus doré
Diagnosis: The species readily differs from the other ptinids studied here in having
the pronotum and elytra entirely obscured by recumbent golden yellow setae
with scattered erect golden ones.
Sexual dimorphism: Sexes are externally similar.
Distribution: Throughout the temperate regions. In Canada the species has
been found in all provinces except Newfoundland.
Economic importance: In Canada the species is found mainly in warehouses,
sometimes in large numbers. It was recorded by Aitken (1975) on Canadian
cargo ships carrying flour.
Pseudeurostus hilleri (Reitter)
Diagnosis: This ptinid differs from the other spider beetles included here mainly
in having the hind trochanter extended to the elytral margin and the elytral
vestiture sparse, consisting of a single row of suberect golden setae on each interval
and stria.
Sexual dimorphism: Males have the last exposed abdominal sternum devoid of
tufts of setae; females have 2 subapical tufts of setae on the last exposed sternum
(Fig. 267).
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