THE AMAZONS AND THEIR SLAVES
Another type of slave-owning ants is represented by the genus
_Polyergus_, found in both Europe and North America, and known as
amazons. Slavery among the amazons is a very different thing from
the casual master-servant relationship found in the various species
of sanguinary ants. The _sanguinea_ are quite able to build nests,
gather food, and rear their young unaided by slave labor, and slaveless
colonies are not at all uncommon, but the amazons are absolutely
dependent upon their slaves, and no amazon colony could exist without
them. As Wheeler says, the amazons “are even incapable of obtaining
their own food, although they may lap up water or liquid food when
this happens to come in contact with their short tongues. For the
essentials of food, lodging and education they are wholly dependent on
the slaves hatched from worker cocoons that they have pillaged from
alien colonies. Apart from these slaves they are quite unable to live,
and hence are always found in mixed colonies inhabiting nests whose
architecture throughout is that of the slave species. Thus the amazons
display two contrasting sets of instincts. While in the home they sit
about in stolid idleness or pass the long hours begging the slaves for
food or cleaning themselves and burnishing their ruddy armor, but when
outside the nest on one of their predatory expeditions they display
a dazzling courage and capacity for concerted action compared with
which the raids of _sanguinea_ resemble the clumsy efforts of a lot of
untrained militia. The amazons may, therefore, be said to represent
a more specialized and perfected stage of _dulosis_ than that of the
sanguinary ants. In attaining to this stage, however, they have become
irrevocably dependent and parasitic.”
The same author describes a slave-hunting foray of the European
species. “The ants leave the nest very suddenly and assemble about
the entrance if they are not, as sometimes happens, pulled back and
restrained by their slaves. Then they move out in a compact column
with feverish haste, sometimes, according to Forel, at the rate of a
meter in 33 seconds, or 3 cm. per second. On reaching the nest to be
pillaged, they do not hesitate like _sanguinea_ but pour into it at
once in a body, seize the brood, rush out again and make for home.
When attacked by the slave species they pierce the heads or thoraces of
their opponents and often kill them in considerable numbers. The return
to the nest with the booty is usually made more leisurely and in less
serried ranks. The observer of one of these forays cannot fail to be
impressed with the marvelous precision of its execution. Although the
ants may occasionally lose their way and have to retrace their steps or
start off in a different direction, they usually make straight for the
nest to be plundered. They must, therefore, like _sanguinea_, possess a
keen sense and memory of locality. There can be little doubt that they
often leave the nest singly and make a careful reconnoissance of the
slave colonies in the vicinity.”
One can hardly believe that as soon as the fighting is over these
warriors relapse into their accustomed lethargy, and are fed and cared
for by their slaves, who often prevent them from leaving the nest,
and sometimes, when they have wandered away, pick them up bodily and
carry them home by main strength. When a colony moves to a new home
the whole enterprise is left to the slaves, who choose and prepare the
new nesting site, and carry the warriors to it. In the case of the
_sanguinea_ it will be remembered that it is the masters who carry the
slaves on these occasions.
An American amazon which has been the subject of considerable study is
_Polyergus breviceps_, found in the mountainous regions of Colorado
and New Mexico. This species is very striking in appearance, the
worker and queen being of a rich purplish-red color, while the male
is jet-black with white wings. A peculiar feature of the _breviceps’_
raiding parties is that there are no casualties on either side. The
slave species offer no real resistance, and the amazons simply put them
gently to one side, take their larvae and pupae, and go their way.
We do not know exactly how new amazon colonies are established. Forel,
Wasmann and Viehmeyer have agreed that the queen lacks the domestic
instinct, and therefore the new colony must be founded by the slave
species, which cares for the amazon females. It has been shown that the
adoption occurs readily enough in artificial nests. Some experiments by
Wheeler gave rather conflicting results, and he closes his discussion
of the matter by saying: “It will be necessary, therefore, to study
this question further before making definite statements in regard to
the method employed by our American amazons in establishing colonies.”