126 
WILD BEES. 
June, 1889. 
place chosen at first is very suitable to the species, and that 
the descendants of the first comers continue to make use of 
this very favourable spot, so long as there remains room for 
their increasing numbers. 
The striking difference between the male and female in 
general appearance in some species is noteworthy. No one, 
for instance, would ever guess that the male and female of 
Andrena fulva belonged to the same species. Many of, if not 
all, the species of Andrena will emit a more or less powerful 
scent on being handled, which is often, but not always, of a 
pleasant nature. This power is by no means peculiar to this 
genus, but is rather the rule throughout the genera of bees 
than the exception ; nor is it confined to one sex as in many 
other insects, Pieris napi for instance, in which the male alone 
has acquired this property. For I know from my own obser¬ 
vations that, in many species at any rate, both sexes have 
this power, but in the case of many others, the males of 
which I have noticed as emitting a powerful odour, I have 
not examined the live females in the field to asertain whether 
they also have this same power. 
With regard to the species of which both sexes emit an 
odour, and I believe most bees belong to this class, we can 
hardly be wrong in assigning a protective value to this 
property. It must be remembered that although to a 
hymenopterist a bee is a bee, and in appearance very distinct 
from other insects, yet there are many enemies of insects 
which would not distinguish perhaps even most bees from 
flies ; and further, it is of course the females only of bees 
which possess a sting, so that the males, especially when they 
possess an appearance rather distinct from the other sex, 
would be very liable to be preyed upon. But even if the 
scent of the male was not in itself disagreeable to certain 
enemies, it is highly probable that in cases where it is of a 
similar nature in both sexes the enemy would associate the 
particular scent with the idea of something harmful, and so 
the male would escape although without a weapon of defence. 
Such a means of escape, too, is all the more important, when 
we consider, that the males of bees emerge generally a week 
or ten days before the appearance of the other sex. 
Of the special enemies of the Andrence there are the 
brightly marked parasitic bees of the genus Nornada. They 
are amongst the most interesting of our native bees. Many 
of the species are very similar in general appearance to wasps, 
having bright yellow bands on a black or brown ground colour, 
the rest are black and brown, often with minute yellow 
markings. 
