in another, during a great part of
April. This constant traffic of the males in the entrance-lobbies of
their houses and the prolonged stay which the bad weather often
compels them to make provide the Sitares with the most favourable
opportunity for slipping into the Bees' fur and taking up their
position. Moreover, when this state of affairs has lasted a month or
so, there can be only very few if any larvae left wandering about
without having attained their end. At that period I was unable to find
them anywhere save on the body of the male Anthophora.

It is therefore extremely probable that, on their emergence, which
takes place as May draws near, the female Anthophorae do not pick up
Sitaris-larvae in the corridors, or pick up only a number which will
not compare with that carried by the males. In fact, the first females
that I was able to observe in April, in the actual neighbourhood of
the nests, were free from these larvae. Nevertheless it is upon the
females that the Sitaris-larvae must finally establish themselves, for
the males upon whom they now are cannot introduce them into the cells,
since they take no part in the building or provisioning. There is
therefore, at a given moment, a transfer of Sitaris-larvae from the
male Anthophorae to the females; and this transfer is, beyond a doubt,
effected during the union of the sexes. The female finds in the male's
embraces both life and death for her offspring; at the moment when she
surrenders herself to the male for the preservation of her race, the
vigilant parasites pass from the male to the female, with the
extermination of that same race in view.

In support of these deductions, here is a fairly conclusive
experiment, though it reproduces the natural circumstances but
roughly. On a female taken in her cell and therefore free from
Sitares, I place a male who is infested with them; and I keep the two
sexes in contact, suppressing their unruly movements as far as I am
able. After fifteen or twenty minutes of this enforced proximity, the
female is invaded by one or more of the larvae which at first were on
the male. True, experiment does not always succeed under these
imperfect conditions.

By watching at Avignon the few Anthophorae that I succeeded in
discovering, I was able to detect the precise moment of their work;
and on the following Thursday,[5] the 21st of May, I repaired in all
haste to Carpentras, to witness, if possible, the entrance of the
Sitares