I INTRODUCTION 9 
in the case of most species, if the nest is uncovered 
cautiously, the moving of the material and the 
sudden flood of light appear not to be noticed, 
though the bees gradually realise that something 
is wrong, and, if left long exposed, will run off in 
search of material with which to re-cover the nest. 
Humble-bees possess, in common with other 

Fic. 1.—A, Portion of posterior margin of fore-wing of Bomdbus muscorum queen, 
seen from beneath. 8, Corresponding anterior margin of hind-wing, seen 
from above. 
bees, various peculiarities of structure adapted for 
special uses that it is hardly within the scope of 
this monograph to describe in detail, but a few of 
the most interesting may be here referred to. 
First may be mentioned the wing-hooks, and | 
cannot do better than quote Bingham’s description 
of these: ‘“ The winged hymenoptera are, as a rule, 
capable of swift and sustained flight. For this 
purpose they possess a wonderful arrangement (one 
of the most beautiful in nature) for linking together, 
during flight, the fore- and hind-wings. Examined 
