The Insects we have spoken of are, however, rather of the nature of ant-cattle, and the fondness of the ants for them is not very remarkable. The relations of the ants to the peculiar species of Insects that live only in or around their nests are much more extraordinary. The greater number of these guests belong to the Order Coleoptera, and of these there are many hundreds—probably many thousands—of species that depend on ants for their existence. The family Pselaphidae furnishes a large number of ants'-nest beetles, and it appears probable that most of them excrete some sugary substance of which the ants are fond. Many of these Pselaphidae are of the most fantastic shapes, more especially the members of the sub-family Clavigerides. But the most curious of all the ant's-nest beetles are the Paussidae, a family exclusively dependent on ants, and having the curious faculty, when disturbed, of bombarding—that is, of discharging a small quantity of vapour or liquid in a state of minute subdivision accompanied by a detonation. Many species of _Staphylinidae_ are peculiar to ant's-nests, and most of them are indifferent or inimical to their hosts, but some of them, such as _Atemeles_ (Fig. 82) and _Lomechusa_, are doubtless producers of sweet stuff that is liked by the ants. The ants feed some of their special favourites amongst these guests in the same manner as they feed one another, viz. by opening the mouth, causing a drop of liquid to appear on the lip, and remaining passive while the guest partakes of the proffered _bonne bouche_. This way of giving food to other individuals is a most remarkable feature in the character of ants; it is not the same system that they adopt in feeding the larvae, for they then make a series of actual movements, and force the nutriment into the mouths of the grubs. Besides the Insects we have mentioned there are also Orthoptera, Hemiptera, Poduridae and Thysanura, Acari, and small Isopod crustaceans that live exclusively in company with ants. We have mentioned that a few Hymenopterous and Dipterous parasites have been detected living at the expense of ants; it is probable that closer observation of the ant larvae and pupae in their nests {183}will disclose a greater number of the parasites of this latter class.