114 
WILD BEES. 
May, 1889. 
with a dense clothing of hairs, which is known as the scopa or 
pollen brush, and in some genera, Anthophora for example, this 
covering is continued over the basal joint of the tarsi as well. 
In the social bees the hairs on the tibia, are so arranged 
as to form a kind of basket in which the moistened pollen 
is carried, and this structure is known as the corbicuium. The 
tibia themselves on their external surface, are smooth and 
slightly concave, the curved stiff hairs being set along the 
margins. 
The parasitic species have no apparatus for collecting 
pollen, and a few industrial genera, Prosopis and Ceratina for 
instance, have the same deficiency, or at least are but ill 
adapted for the purpose ; the bees belonging to these two 
genera store up a semi-liquid honey in place of the usual 
pollen mass. 
But it is not on the tibia alone that there is a special 
arrangement for gathering pollen. In some bees a pollen¬ 
brush is situated on the terminal abdominal segments beneath, 
and it is noticeable that these have the most highly developed 
instincts and the most interesting habits of all our British 
species. These, then, are the most important structures for 
pollen gathering, but many other parts assist in the work. 
The long “ jioccus" on the trochanter of Andrena, and the 
thoracic hairs may be mentioned, especially those on the sides 
of the metathorax, which in some species are very long and 
curved, and beautifully plumose, as in Andrena dorsata for 
instance, and which are often loaded with pollen. Indeed, 
some species cover themselves so entirely as to be hardly 
recognisable, particularly those which frequent the blossoms 
of Hieracium and other yellow Composita. Andrena humilis 
is a remarkable instance of this, for hundreds of these bees 
may be seen on a fine day round a populous colony, each one 
appearing entirely yellow from the covering of pollen collected 
from the hawk weeds. 
Every one knows how important insects are for the 
fertilisation of flowers ; and bees, since their food is entirely 
obtained from this source, are the most important agents in 
this work, and in general are the best adapted for it, because 
of their hairy exterior and the peculiar character of these 
hairs. Certainly, though bees are greatly indebted to 
flowering plants, the latter derive the greatest benefit from the 
visit of bees, and I imagine that a bee can rarely visit a flower 
without effecting that object, which the plant, by the 
attractions it offers, has striven to attain. One must also take 
into account the methodical habits of bees in visiting one 
kind of flower at a time, and not first one species and then 
