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704 COLLEGE ENTOMOLOGY
in nearly straight line across the vertex. Legs short and hairy; with pollen
basket; calcaria of hind tibia: equal and half as long as the first tarsal segment;
middle tarsal segments wide. Fore wings with one radial and three submarginal
cells. Abdomen broadly triangular; segment VI exserted.
These bees nest in sandy or clayey soil or rarely in chinks in mortar and
sometimes form large colonies. The burrows are from 8 to 10 in. long, line,j with
a thin gelatinous and quick-drying fluid, divided into from five to eight cells,
one above the other, and are provisioned with a mixture of pollen and honey.
The adults visit many kinds of flowers and are of considerable economic importance
as pollinizers. The family is a relatively small one, represented in many
parts of the world, but it appears to reach its greatest development in Australia,
where there are 137 species, mostly belonging to the genus Paracolletes Smith.
The genus Colletes Latr. is the commonest in the Holarctic region.
Family PROSOPIDIDlE 1 (Dalla Torre 1896) Rayment 1935 (Pro'so-pid'i-dre,
from the Greek ?rp0O-C>,)?r(s, 7TpO£JW7T(OOS, mask; because of the fanciful
resemblance of their faces to human faces). Yellow-faced Bees, Obtusetongued
Bees.
Small slender bees, 3.5-8.0 mm.: polished or with little pubescence; mostly
blac1e with the faces, particularly of the males, marked with white or yellow.
FIG. 252. An obtuse-tongued bee, PrasnjJis
crJ1'lspiclia Mctz. (After Woodworth from Insects
Df Western North America.)
They are considered to be primitive
members of the superfamily and have
the mouth parts only slightly specialized.
Tongue short and broad, except
in the males of certain genera. Legs
without pollen-collecting mechanisms.
Wings with two submarginal cells.
Abdomen of males with special developments
on the ventral plates of
segments VII and VIn which are of
taxonomic value in separating species.
This is a small family of bees with
few genera but a large number of
species which have a cosmopolitan
distribution. They nest in pithy
stems, in holes in the ground, or in
chinks in walls in buildings. Their
cells are lined with a quick-drying
translucent fluid which retains the liqllid mixture of honey and pollen. The
adults emit a characteristic odor. They are of some value as pollinizers of
plants. The most important genus is Prosopis Fab. (Hylreus Fab.)
1 The name HYLJEIDiE is frequently used for this family based on the fact that the genus
Hy/reus Fab. 1793 antedates Prasopis Fab. 1804. This family name was first employed by
Viereck in 1916. In view of the fact that the Royal Entomological Society of London haa
. petitioned the International Commission of Zolilogical Nomenclature to reject the name
Bylreus, it bas seemed wise to retain the more generally used family name, PROSOPIDIDJE
(PROSOPIDlE).. .