with very large jaws. These latter are generally supposed to act as soldiers, and the size of the head enables the muscles which move the jaws to be of unusual dimensions, though the little ones are also very pugnacious. This differentiation of certain individuals so as to adapt them to special functions seems to me very remarkable; for it must be remembered that the difference is not one of age or sex.
The food of ants consists of insects—great numbers of which they destroy—of honey, honey-dew, and fruit; indeed, scarcely any animal or sweet substance comes amiss to them. Some species—such, for instance, as the small brown garden ant—ascend bushes in search of aphides. The ant then taps the aphis gently with her antennæ, and the aphis emits a drop of sweet fluid, which the ant drinks. Sometimes the ants even build covered ways up to and over the aphides, which, moreover, they protect from the attacks of other insects. Our English ants do not collect provision for the winter—indeed, their food is not of a nature which would admit of this. Some southern species, however, collect grain, occasionally in considerable quantities. Moreover, though our English ants cannot be said exactly to lay up stores, some at least do take steps to provide themselves with food in the future. The small yellow meadow ant (Lasius flavus), for instance, lives principally on the honey-dew of certain aphides which suck the roots of grass. The ants collect the aphides in the nest, not only watching over them themselves, but, as I have been able to satisfy myself, even over their eggs—an act which one is much tempted to refer to forethought, and which in such a case implies a degree of prudence superior to that of some savages. Besides these aphides, many other insects live in ants' nests. If they are to be regarded as domestic animals, then ants have more domestic animals than we have. The majority of these ant-guests are beetles. Some of them—as, for instance, the curious little Claviger—are quite blind, and are only found in ants' nests, the ant taking just as much care of them as of their own young. It is evident, therefore, that in some way they are useful or agreeable to the ants. The subject, however, is one as yet but little understood, and very difficult to study. Grimm and Lespés consider that some of these beetles secrete a sweet fluid like the aphides, and from analogy this seems probable. Other creatures which habitually live in ants' nests, like the little Beckia albinos or the blind woodlouse (Platyarthrus), perhaps make themselves useful as scavengers.
Nor are ants without their enemies. In addition to birds and other larger foes, if you disturb a nest of the brown ants at any time during the summer, you will probably see some very small flies hovering over them, and every now and then making a dash at some particular ant. These flies belong to the genus Phora, and to a species hitherto unnamed, which Mr. Verrall has been good enough to describe for me. They lay their eggs on the ants, inside which