_ to
steal the larvae which serve it as food, but the _Formica_ is too large
to pursue the thief when it returns to its own galleries.

_Slaves._--Several species of ants are found in association with another
species which stands to them in the relation of slave to master.
_Formica sanguinea_ is a well-known European slave-making ant that
inhabits England; its workers raid the nests of _F. fusca_ and other
species, and carry off to their own nests pupae from which workers are
developed that live contentedly as slaves of their captors. _F.
sanguinea_ can live either with or without slaves, but another European
ant (_Polyergus rufescens_) is so dependent on its slaves--various
species of _Formica_--that its workers are themselves unable to feed the
larvae. The remarkable genus _Anergates_ has no workers, and its
wingless males and females are served by communities of _Tetramorium
cespitum_ (fig. 3).

[Illustration: FIG. 3.--Ant, _Tetramorium cespitum_ (Linn.), a, Female;
b, female after loss of wings; c, male; d, worker; e, larva; g, pupa; f,
head of larva more highly magnified. After Marlatt, _Bull_. 4 (n.s.)
_Div. Ent. U.S. Dept. Agriculture_]

_Senses and Intelligence of Ants._--That ants possess highly developed
senses and the power of communicating with one another has long been
known to students of their habits; the researches of P. Huber and Sir J.
Lubbock (Lord Avebury) on these subjects are familiar to all
naturalists. The insects are guided by light, being very sensitive to
ultra-violet rays, and also by scent and hearing. Recent experiments by
A.M. Fielde show that an ant follows her own old track by a scent
exercised by the tenth segment of the feeler, recognizes other inmates
of her nest by a sense of smell resident in the eleventh segment, is
guided to the eggs, maggots and pupae, which she has to tend, by
sensation through the eighth and ninth segments, and appreciates the
general smell of the nest itself by means of organs in the twelfth
segment. Lubbock's experiments of inducing ants to seek objects that had
been removed show that they are guided by scent rather than by sight,
and that any disturbance of their surroundings often causes great
uncertainty in their actions. Ants invite one another to work, or ask
for food from one another, by means of pats with the feelers; and they
respond to the solicitations of their guest--beetles or mites, who ask
for food by patting the ants with their feet. In all