differences in manner and disposition. We know, for example,
that the horse-ant (_Formica rufa_, Fig. 3) has little _individual_
intelligence, but is extremely socialistic, and moves and acts _en
masse_ with precision and tact. Another species (_F. fusca_) is timid
and retiring. _F. pratensis_ is a revengeful creature, since it
"worries" its fallen foes; _F. cinerea_ is bold and audacious; others
are termed "thieves" and "cowards"; some are phlegmatic; and to
complete the list of failings and traits which are human enough in
character, one species is said to present an invariable greediness as
its prevailing characteristic. The common ants resemble the termites
in the general details of their life. We see in an ant's nest the same
restless activity of the workers, the same earnest attention paid to
the young and pupae, the same instinct in shielding the young from
danger, and much the same general routine of development. Certain
rather special, and it may be said extraordinary, habits of ants may,
however, demand notice before we attempt a brief survey of their
instincts at large. Few readers are unacquainted with the _Aphides_,
or plant-lice, those little wingless insects which infest our plants
and herbs in myriads in summer. It is a fact now well known to
naturalists, and first placed on record by Huber, that between the
ants and plant-lice, relations of a very friendly and, as far as the
ants are concerned, advantageous character have become established.
Ants have been observed to stroke the tips of the bodies of the
plant-lice with their antennae, this act causing the plant-lice to
exude drops of a clear, sweet fluid, of which the ants are extremely
enamoured. The ants would thus appear to habitually "milk" their
insect-neighbors, and, as far as observation goes, some ants seem not
merely to keep the plant-lice in their nests so as to form a veritable
dairy establishment, but also to make provision in the future by
securing the eggs of the aphides, and bringing up the young as we rear
calves.

[Illustration: FIG 4. APPLE APHIS (_Eriosoma Mali_).]

That the relation between the ants and plant-lice are of very stable
kind is proved by the interesting remarks of Mr. Darwin, who "removed
all the ants from a group of about a dozen aphides on a dock-plant,
and prevented their attendance during several hours." Careful watching
showed that the plant-lice after this interval did not excrete the
sweet fluid. Mr. Darwin th