We had brought into our garden in the beginning of Jnne, a large piece of a willow tree, which had been very curiously worked out by the species tumidly called the Emmet (F. fuliginosa, Latreille). The tree indeed from which it bad been taken, appeared to have been destroyed in a great measure from the extensive excavations of these little carpenters. Yet the portion of the tree alluded to seemed to be singularly strong, when the great number of the cells and their peculiar structure was taken into consideration. The walls of these cells were literally as thin as writing•paper, though not quite so smooth and even, and they were seldom quite parallel, but arranged, some perpendicularly, and others slanting in various directions, worked out, it would appear, upon no previous design, but beginning at any given point, and only limited in extent by the worker discovering hie approach to one adjacent. The tact with which they chisel away the wood with their jaws, so as to come so near the next cell without actually cutting into it, cannot well be accounted for on any of the common principles of human mechanism. It cannot be the result of vision, from the worker-out looking along the level of the plane, as one of our carpenters would do, and thence working so as not to cut through it ; for the wall has, in most instances, though not in all, no free edge along which such a level could be taken by the eye. Hearing might assist them however, supposing workers to be engaged in chiselling on each side of the partition, but it would appear to be more from touch, or rather that modification of it denominated tact, which enables them to feel, as it were, when they have nearly penetrated the wall, and which consequently warns them to stop.
It is not a little remarkable, that all the wood which is worked out by these ants is tinged of a black colour, giving all their streets and lanes somewhat the appearance of having suffered from fire or of being smoked. M. Huber the younger did not succeed in ascertaining the cause of this black colour. We should conjecture it to arise from iron contained in the saliva of the ante acting on the gallic acid of the wood, in a similar way as the same wood becomes black when cut with a knife. The fine glossy black of the ants themselves may originate from the same chemical principle, and this is rendered more probable from the excavations made by other species, such as the Dusky Ant (F. fusea, Latreille), not being tinged with this black colour. Neither are the excavations of the latter so regular in the form of the cells ; and the delicately thin partitions do not occur. We have seen several colonies of the Yellow Ant (P. /tura, Latreille) established in trees, though their usual habits lead them to prefer a hedge-bank, the dry ridge of a field, or a small knoll on a common. In none of these however had the workers much trouble in making their excavations, the trees being in every instance far gone with the dry rot, and the chambers were consequently as easy to construct as in a knoll of sand. In the instance of the Black Carpenter-Ant
(F. fuliginosa), on the other hand, the wood of the tree selected for their colony is always hard and tough, the easiness of working it being apparently considered a disadvantage rather than a recommendation. We have usually seen these colonies, therefore, in growing trees, the oak seeming to be preferred to all others ; the honeycomb-like work does not seem to stop the vegetation, the tree continuing to put forth leaves and shoots as before it was excavated for the use of the colony. In the instance which gives rise to these remarks, the willow tree was indeed dilapidated and shorn of its leaves and branches, yet was it untouched with dry rot, and the wood was hard and tough.
Food of Ants.—Some species of ants are carnivorous and will eat insects, fruits, and almost anything eaten by other animals ; but honey is the most universal favourite among all the species, particularly the excretion of the various species of Aphides, called Honey-Dew. It is on this account that, wherever Aphides abound, we are always certain to meet with ants carefully attending their motions and greedily drinking the honey-dew, which becomes so injurious to plants when it increases in quantity so as to obstruct the pores of the leaves. It is stated by Huber and some other authors, that during winter the ants imprison some Aphides in their cells, or, at all events, take advantage of individuals of the Grass Aphis (Aphis graminum) in the vicinity of their hills to obtain honey-dew. We strongly suspect there must be some fallacy in this statement ; for among numerous colonies which we have carefully examined during winter, we always found the whole population torpid or nearly so, and not inclined to touch even honey when we offered it to them. In the case of the Sanguinary Ants in Germany already mentioned, we have seen that they had become torpid as early as October, when the weather was still fine and far from being cold. We are therefore of opinion that the statement will be found as void of accurate foundation as that which represents ants as storing up corn for the winter.
Migrations.—We have already seen, under the head of pairing, one principle in operation for spreading around a parent ant-hill a number of young colonies. This indeed may be considered the main principle of migration ; but besides this, the whole of a populous ant-hill which has been established for several years will, from some cause beyond our means of tracing, though most probably on account of more convenient forage, at once desert their homes and march to a new station. Among the Yellow Ants, the Emmets, and the Wood Ants or Pismires, this is by no means common ; but it is an every day occurrence among the Red Ants, the Ash-Coloured Ants, the Turf Ants, and others whose colonies never become very populous, and are consequently both more easily moved and more easily provided with lodging.