aperda beetle, neither of which bears
any outward resemblance to the larva of the wasps.

Seeing that identity of shape and costume does not save the Polistes,
how will the Volucella fare, with her clumsy imitation? The wasp's eye,
which is able to discern the dissimilar in the like, will refuse to
be caught. The moment she is recognized, the stranger is killed on the
spot. As to that there is not the shadow of a doubt.

In the absence of bumblebee flies at the moment of experimenting, I
employ another fly, Milesia fulminans, who, thanks to her slim figure
and her handsome yellow bands, presents a much more striking likeness to
the wasp than does the fat Volucella zonaria. Despite this resemblance,
if she rashly venture on the combs, she is stabbed and slain. Her yellow
sashes, her slender abdomen deceive nobody. The stranger is recognized
behind the features of a double.

My experiments under glass, which varied according to the captures which
I happened to make, all lead me to this conclusion: as long as there
is more propinquity, even around the honey, the other occupants are
tolerated fairly well; but, if they touch the cells, they are assaulted
and often killed, without distinction of shape or costume. The grubs'
dormitory is the sanctum sanctorum which no outsider must enter under
pain of death.

With these caged captives I experiment by daylight, whereas the free
wasps work in the absolute darkness of their underground retreat. Where
light is absent, color goes for nothing. Once, therefore, that she has
entered the cavern, the bumblebee fly derives no benefit from her yellow
bands, which are supposed to be her safeguard. Whether garbed as she is
or otherwise, it is easy for her to effect her purpose in the dark, on
condition that she avoids the tumultuous interior of the wasps' nest. So
long as she has the prudence not to hustle the passers by, she can dab
her eggs, without danger, on the paper wall. No one will know of her
presence. The dangerous thing is to cross the threshold of the burrow
in broad daylight, before the eyes of those who go in and out. At that
moment alone, protective mimicry would be convenient. Now does the
entrance of the Volucella into the presence of a few wasps entail such
very great risks? The wasps' nest in my enclosure, the one which
was afterwards to perish in the sun under a bell glass, gave me the
opportunity for prolonged observations, but without any result upon the
subject of