both nests, the little ants attacked their big neighbours with
surprising courage. Now I was curious to ascertain whether F. sanguinea
could distinguish the pup of F. fusca, which they habitually make into
slaves, from those of the little and furious F. flava, which they
rarely capture, and it was evident that they did at once distinguish
them: for we have seen that they eagerly and instantly seized the pup
of F. fusca, whereas they were much terrified when they came across the
pup , 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 pup .
One evening I visited another community of F. sanguinea, and found a
number of these ants entering their nest, carrying the dead bodies of
F. fusca (showing that it was not a migration) and numerous pup . I
traced the returning file burthened with booty, for about forty yards,
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 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 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 larv ,
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 larv . So that the
171