stir
from the point which they have selected, a point near the Bee's
shoulders. We do not see them wandering from spot to spot, exploring
the Anthophora's body, seeking the part where the skin is more
delicate, as they would certainly do if they were really deriving some
nourishment from the juices of the Bee. On the contrary, they are
nearly always established on the toughest and hardest part of the
Bee's body, on the thorax, a little below the insertion of the wings,
or, more rarely, on the head; and they remain absolutely motionless,
fixed to the same hair, by means of the mandibles, the feet, the
closed crescent of the eighth segment and, lastly, the glue of the
anal button. If they chance to be disturbed in this position, they
reluctantly repair to another point of the thorax, pushing their way
through the insect's fur and in the end fastening on to another hair,
as before.

To confirm my conviction that the young Sitaris-grubs do not feed on
the Anthophora's body, I have sometimes placed within their reach, in
a glass jar, some Bees that have long been dead and are completely
dried up. On these dry corpses, fit at most for gnawing, but certainly
containing nothing to suck, the Sitaris-larvae took up their customary
position and there remained motionless as on the living insect. They
obtain nothing, therefore, from the Anthophora's body; but perhaps
they nibble her fleece, even as the Bird-lice nibble the birds'
feathers?

To do this, they would require mouth-parts endowed with a certain
strength and, in particular, horny and sturdy jaws, whereas their jaws
are so fine that a microscopic examination failed to show them to me.
The larvae, it is true, are provided with powerful mandibles; but
these finely-pointed mandibles, with their backward curve, though
excellent for tugging at food and tearing it to pieces, are useless
for grinding it or gnawing it. Lastly, we have a final proof of the
passive condition of the Sitaris-larvae on the body of the Anthophorae
in the fact that the Bees do not appear to be in any way incommoded by
their presence, since we do not see them trying to rid themselves of
the grubs. Some Anthophorae which were free from these grubs and some
others which were carrying five or six upon their bodies were placed
separately in glass jars. When the first disturbance resulting from
their captivity was appeased, I could see nothing peculiar about those
occupied by the young Sitares. And, if all t