e, and it was evident that they did at once distinguish them;
for we have seen that they eagerly and instantly seized the pupae of F.
fusca, whereas they were much terrified when they came across the pupae,
or even the earth from the nest, of F. flava, and quickly ran away; but
in about a quarter of an hour, shortly after all the little yellow ants
had crawled away, they took heart and carried off the pupae.

One evening I visited another community of F. sanguinea, and found a
number of these ants returning home and entering their nests, carrying
the dead bodies of F. fusca (showing that it was not a migration) and
numerous pupae. I traced a long file of ants burdened with booty, for
about forty yards back, to a very thick clump of heath, whence I saw the
last individual of F. sanguinea emerge, carrying a pupa; but I was not
able to find the desolated nest in the thick heath. The nest, however,
must have been close at hand, for two or three individuals of F. fusca
were rushing about in the greatest agitation, and one was perched
motionless with its own pupa in its mouth on the top of a spray of
heath, an image of despair over its ravaged home.

Such are the facts, though they did not need confirmation by me, in
regard to the wonderful instinct of making slaves. Let it be observed
what a contrast the instinctive habits of F. sanguinea present with
those of the continental F. rufescens. The latter does not build its own
nest, does not determine its own migrations, does not collect food
for itself or its young, and cannot even feed itself: it is absolutely
dependent on its numerous slaves. Formica sanguinea, on the other
hand, possesses much fewer slaves, and in the early part of the summer
extremely few. The masters determine when and where a new nest shall
be formed, and when they migrate, the masters carry the slaves. Both in
Switzerland and England the slaves seem to have the exclusive care of
the larvae, and the masters alone go on slave-making expeditions. In
Switzerland the slaves and masters work together, making and bringing
materials for the nest: both, but chiefly the slaves, tend and milk
as it may be called, their aphides; and thus both collect food for
the community. In England the masters alone usually leave the nest to
collect building materials and food for themselves, their slaves and
larvae. So that the masters in this country receive much less service
from their slaves than they do in Switzerland.

By