An Introduction to Entomology: Vol. 2 / or Elements of the Natural History of the Insects

by William Kirby; William Spence

Not only the aphides yield this repast to the ants, but also the Cocci, with whom they have recourse to similar manœuvres, and with equal success; only in this case the movement of the antennæ over their body may be compared to the thrill of the finger over the keys of a piano-forte.

But you are not arrived at the most singular part of this history,—that ants make a property of these cows, for the possession of which they contend with great earnestness, and use every means to keep them to themselves. Sometimes they seem to claim a right to the aphides that inhabit the branches of a tree or the stalks of a plant; and if stranger-ants attempt to share their treasure with them, they endeavour to drive them away, and may be seen running about in a great bustle, and exhibiting every symptom of inquietude and anger. Sometimes, to rescue them from their rivals, they take their aphides in their mouth, they generally keep guard round them, and when the branch is conveniently situated, they have recourse to an expedient still more effectual to keep off interlopers,—they inclose it in a tube of earth or other materials, and thus confine them in a kind of paddock near their nest, and often communicating with it.

The greatest cow-keeper of all the ants, is one to be met with in most of our pastures, residing in hemispherical formicaries, which are sometimes of considerable diameter. I mean the yellow ant of Gould (F. flava). This species, which is not fond of roaming from home, and likes to have all its conveniences within reach, usually collects in its nest a large herd of a kind of Aphis, that derives its nutriment from the roots of grass and other plants (Aphis radicum); these it transports from the neighbouring roots, probably by subterranean galleries, excavated for the purpose, leading from the nest in all directions[89]; and thus, without going out, it has always at hand a copious supply of food. These creatures share its care and solicitude equally with its own offspring. To the eggs it pays particular attention, moistening them with its tongue, carrying them in its mouth with the utmost tenderness, and giving them the advantage of the sun. This last fact I state from my own observation; for once upon opening one of these ant-hills early in the spring, on a sunny day, I observed a parcel of these eggs, which I knew by their black colour, very near the surface of the nest. My attack put the ants into a great ferment, and they immediately began to carry these interesting objects down into the interior of the nest. It is of great consequence to them to forward the hatching of these eggs as much as possible, in order to ensure an early source of food for their colony; and they had doubtless in this instance brought them up to the warmest part of their dwelling with this view. M. Huber, in a nest of the same ant, at the foot of an oak, once found the eggs of Aphis Quercûs.

Our yellow ants are equally careful of their Aphides after they are hatched, when their nest is disturbed conveying them into the interior, fighting fiercely for them if the inhabitants of neighbouring formicaries, as is sometimes the case, attempt to make them their prey; and carrying them about in their mouths to change their pasture, or for some other purpose. When you consider that from them they receive almost the whole nutriment both of themselves and larvæ, you will not wonder at their anxiety about them, since the wealth and prosperity of the community is in proportion to the number of their cattle. Several other species keep Aphides in their nests, but none in such numbers as those of which I am speaking[90].

When the population exceeds the produce of a country, or its inhabitants suffer oppression, or are not comfortable in it, emigrations frequently take place, and colonies issue forth to settle in other parts of the globe; and sometimes whole nations leave their own country, either driven to this step by their enemies, or excited by cupidity to take possession of what appears to them a more desirable residence. These motives operate strongly on some insects of the social tribes.—Bees and ants are particularly influenced by them. The former, confined in a narrow hive, when their society becomes too numerous to be contained conveniently in it, must necessarily send forth the redundant part of their population to seek for new quarters; and the latter—though they usually can enlarge their dwelling to any dimensions which their numbers may require, and therefore do not send forth colonies, unless we may distinguish by that name the departure of the males and females from the nest—are often disgusted with their present habitation, and seek to establish themselves in a new one:—either the near neighbourhood of enemies of their own species; annoyance from frequent attacks of man or other animals; their exposure to cold or wet from the removal of some species of shelter; or the discovery of a station better circumstanced or more abundant in aphides;—all these may operate as inducements to them to change their residence. That this is the case might be inferred from the circumstance noticed by Gould[91], which I have also partly witnessed myself, that they sometimes transport their young brood to a considerable distance from their home. But M. Huber, by his interesting observations, has placed this fact beyond all controversy; and his history of their emigrations is enlivened by some traits so singular, that I am impatient to relate them to you. They concern chiefly the great hill-ant (F. rufa), though several other species occasionally emigrate.

Some of the neuters having found a spot which they judge convenient for a new habitation, apparently without consulting the rest of the society, determine upon an emigration, and thus they compass their intention: The first step is to raise recruits:—with this view they eagerly accost several fellow citizens of their own order, caress them with their antennæ, lead them by their mandibles, and evidently appear to propose the journey to them. If they seem disposed to accompany them, the recruiting officer, for so he may be called, prepares to carry off his recruit, who, suspending himself upon his mandibles, hangs coiled up spirally under his neck;—all this passes in an amicable manner after mutual salutations. Sometimes, however, the recruiter takes the other by surprise, and drags him from the ant-hill without giving him time to consider or resist. When arrived at the proposed habitation, the suspended ant uncoils itself, and, quitting its conductor, becomes a recruiter in its turn. The pair return to the old nest, and each carries off a fresh recruit, which being arrived at the spot joins in the undertaking:—thus the number of recruiters keeps progressively increasing, till the path between the new and the old city is full of goers and comers, each of the former laden with a recruit. What a singular and amusing scene is then exhibited of the little people thus employed! When an emigration of a rufescent colony is going forward, the negroes are seen carrying their masters: and the contrast of the red with the black renders it peculiarly striking. The little turf-ants (Myrmica? cæspitum) upon these occasions carry their recruits uncoiled, with their head downwards and their body in the air.

This extraordinary scene continues several days; but when all the neuters are acquainted with the road to the new city, the recruiting ceases. As soon as a sufficient number of apartments to contain them are prepared, the young brood, with the males and females, are conveyed thither, and the whole business is concluded. When the spot thus selected for their residence is at a considerable distance from the old nest, the ants construct some intermediate receptacles, resembling small ant-hills, consisting of a cavity filled with fragments of straw and other materials, in which they form several cells; and here at first they deposit their recruits, males, females, and brood, which they afterwards conduct to the final settlement. These intermediate stations sometimes become permanent nests, which however maintain a connexion with the capital city[92].

While the recruiting is proceeding it appears to occasion no sensation in the original nest; all goes on in it as usual, and the ants that are not yet recruited pursue their ordinary occupations: whence it is evident that the change of station is not an enterprise undertaken by the whole community. Sometimes many neuters set about this business at the same time, which gives a short existence (for in the end they all reunite into one) to many separate formicaries. If the ants dislike their new city, they quit it for a third, and even for a fourth: and what is remarkable, they will sometimes return to their original one before they are entirely settled in the new station; when the recruiting goes in opposite directions, and the pairs pass each other on the road. You may stop the emigration for the present, if you can arrest the first recruiter, and take away his recruit[93].

I shall now relate to you some other portions of Myrmidonian History, which, though perhaps not so striking and wonderful as the preceding details, are not devoid of interest, and will serve to exemplify their incredible diligence, labour, and ingenuity.

In this country it is commonly in March, earlier or later according to the season, that ants first make their appearance, and they continue their labours till the middle or latter end of October. They emerge usually from their subterranean winter-quarters on some sunny day; when, assembling in crowds on the surface of the formicary, they may be observed in continual motion, walking incessantly over it and one another, without departing from home; as if their object, before they resumed their employments, was to habituate themselves to the action of the air and sun[94]. This preparation requires a few days, and then the business of the year commences. The earliest employment of ants is most probably to repair the injuries which their habitation has received during their state of inactivity: this observation more particularly applies to the hill-ant (F. rufa), all the upper stories of whose dwellings are generally laid flat by the winter rains and snow; but every species, it may well be supposed, has at this season some deranged apartments to restore to order, or some demolished ones to rebuild.