Once a Week (magazine)/Series 1/Volume 7/The wood ant
THE WOOD ANT.
Within a reasonable walk of my house there is a small wood which affords opportunities of watching the habits of many creatures. It is planted upon more than one kind of soil, so that a plentiful variety of plants is found within its limits, and, as a necessary consequence, many insects live upon the plants, predacious insects come to eat their harmless kinsfolk, and birds come to eat both the cannibals and their victims.
This place is a favourite resort of the wood-ants, which have built their fragile yet enduring nests in many sheltered spots, and have driven their wonderful paths through almost every part of the wood. For some years I have passed many pleasant hours every summer among the trees, and found the day only too short for the many observations that came under my notice. The best way to take advantage of a wood is to set out with the intention of watching some particular creature, and to give up one’s time exclusively to that single object; not failing, of course, to mark any point of interest that may present itself respecting other beings that may come within ken, and to jot it down in a note-book.
This insect, which may be known by its large size and reddish thorax, is one of the stingless ants, though it is quite as formidable an antagonist as the species which possess those sharp and envenomed darts. For, though the wood ant has no sting, it yet has a store of poison, and can use its venomous powers effectively, though in a more roundabout manner than is adopted by the sting-bearers. It is a must fierce and determined creature, the sense of fear seeming to have been wholly omitted from its composition. It will attack any thing and any body without the least hesitation, and possesses all the courage without the cunning exhibited by the Lilliputians in their memorable attack on the Man Mountain. For a man is to the wood-ant not only a moving mountain, but a moving world; and yet there is not a single ant that will not attack a man, if it fancies him to be in too close proximity to its residence.
Urged by some wonderful instinct, it makes at once for the nearest unprotected skin, bites fiercely with its sharp and calliper-shaped jaws, and simultaneously bending its body so as to bring the tip of the abdomen to bear upon the wound, squirts a small drop of its poison into the cavity, producing for the time, a sharp and painful smarting sensation. The pain, however, is very transient, although, at the moment it is inflicted, the pang is quite as severe as that inflicted by the sting of a wasp. Nor is this its only mode of attack. The wood ant is able to eject this poisonous substance to some distance, and if a nest be broken open, and a bare hand placed within the aperture, it will be speedily covered with a thousand little dots of pungent fluid, and if the skin be very sensitive, will smart as though it had been plunged into a bunch of stinging nettles. The scent of this fluid is strongly acid, like highly concentrated vinegar, and even at the distance of a yard from the nest produces an unpleasant sensation in the throat and nostrils. One of my friends, desirous of testing personally the peculiar scent, made a breach in the nest of the wood-ant, and put his face to the hole. Scarcely had he approached within three inches than he started back, vowing that the ants had stung him all over his chin, and could not for some time be convinced of his error.
This pungent liquid is acid in its nature, and, when analysed, is found to contain two kinds of acid, one peculiar to the insect and called formic acid, and the other the substance termed malic acid, which gives to the juice of apples its peculiar flavour. Not only has it the scent of vinegar, but a very good substitute for that useful article is often made by steeping successive measures of the wood-ant in boiling water. The substance called chloroform owes its name to the similarity between its constituent elements and those of formic acid. In chemical language, though not in chemical formula, formic acid consists of two atoms carbon, one atom hydrogen, and two atoms oxygen; while the composition of chloroform is two atoms carbon, one atom hydrogen, and three atoms chlorine. It may be casually remarked that formic acid can be produced by artificial means.
The nest of this insect is a wonderfully large structure when the size of the tiny architects is taken into consideration, and the regularity with which their interior is parcelled out into chambers and galleries, is not less surprising. It is made of little pieces of stick, dried leaves, broken stems of the dry fern, and always contains the berries of the mountain ash, if any tree of this kind should happen to be within a moderate distance. When I first observed the dog berries amid the heap of leaves and sticks, I thought that they had fallen from a neighbouring tree and been accidentally blown upon the nest, but I have since found that every nest in the wood contains these berries, when a mountain ash is within forty or fifty yards. Their use I cannot imagine, as the ants do not carry them into the nest, but merely mix them with the dried substances of the exterior.
The materials of which the nest is composed are heaped quite loosely and apparently at random on each other. But if the nest be carefully examined, a certain order is to be detected, particularly in the entrances and galleries, which are all made of long sticks widely arranged across each other, so as to form a five-sided aperture. If a twig be brought to the nest, its destination is nearly sure to be at one of the many openings. Being desirous of ascertaining whether the ants would accept extraneous assistance, I broke off a little dried stick to the shape and size of those that were arranged about the aperture, and laid it upon the others so as to match them as nearly as possible. A posse of ants immediately came to look at the new addition, took hold of it with their jaws, and after making a trifling alteration—for form’s sake, I suppose, lest I should be too conceited about my architectural skill—they allowed it to remain.
It is most interesting to watch the ants bringing materials for their home. If an ant finds a little piece of broken fern stem that is suitable for the outer wall, he picks it up by one end, holds it out straight before him as if he were smoking a very large cigar, and sets off briskly homewards. This mode of carrying his burden is evidently adopted for the convenience of steering it through the grass blades, fallen fern, and other impediments, which, trifling as they appear to human eyes, are by no means insignificant to the ants. I have even seen an ant carrying off a grub three times its own size, holding it in the same manner; the strength required for such a feat is truly enormous.
But when a heavier or larger burden, such as a piece of stick, has to be transported, a different plan is adopted. Six or seven ants are detached for the work, and they set about it with a unity of purpose that is really surprising. Grasping it with their jaws, they gradually edge it onward in the right direction, one of their number always seeming to act as foreman, and taking hold of the end, which seems to be the post of honour. As long as the ground is tolerably even, the stick is dragged along without difficulty, and the foreman or “ganger” cannot be distinguished from his fellows, save by his position at the end of the stick. But when they get among broken ground, or if the stick should perchance fall into a crevice, and carry its bearers with it, the ganger seldom touches the stick except to pull it into the proper direction, but runs ahead to reconnoitre, then returns to the gang, and is all life and animation. I have seen the clever little creatures make a mistake, and get the stick into a labyrinth of broken ferns and twigs, through which they could by no means steer it, and then seen them carefully return by the same path until they were clear of the thicket, and choose another and a smoother road.
On one occasion I watched a gang of ants, six in number, that had jammed their burden so tightly under a fern stem that they could proceed no further. They immediately tried to extricate it, but were checked by an angular bend in the stick, which had hitched itself under the fern, and prevented it from being moved in either direction. Being curious to know how the ants would surmount the difficulty, and rather fancying that they would leave the stick and fetch another, I watched them for nearly two hours. They evidently had no intention of relinquishing their task, and after a vast amount of excitement, the ganger getting on the top of the stick and down again about fifty times, they hauled the projecting extremity down by main force of numbers, dragged it from below the impediment, and, I suppose, got it safely home. The stick was a trifle more than two inches in length, about as thick as a stout crowquill, and at one end had a knot and a sharp bend upwards. An idea of the strength exerted in the transportation of this burden may be formed by taking the comparative sizes of men and ants, magnifying the piece of stick into a tree trunk of corresponding dimensions, and setting six men to carry that trunk through a virgin forest, and over ravines and precipices, up mountains and down valleys, and lastly to the top of a building shaped something like the great pyramid, but much more lofty, the sides of which are formed of loose sticks and logs.
Nothing short of taking away the object of their labours, seems to divert these industrious creatures from their work. I have laid large flies, little grubs, and other attractive articles of diet in their way, but they suffer them to remain unheeded, though, if unemployed on serious business, they would carry off such prey as soon as they saw it.
The wood ants seem to be acquainted with the leading principles of civilisation, their nest being the centre of a radiating system of roads, extending for a wonderful distance, and as permanent in their way as Watling Street, or any of the old Roman roads which now traverse our land. Mr. William Hewitt tells me that he has watched one of these roads for more than twenty years, and found that on every fine day it was crowded with ants going off for plunder, or returning laden with spoils for the benefit of the community. Even on wet and cold days, when the ants, who are chilly beings, wisely stay at home, their roads are plainly perceptible, and are marked out by their freedom from bits of stick, leaves, &c., these having been removed by the insects as materials for their nest. It is always easy to find the nest by following up the road, and the right direction can be at once learned by following the course adopted by the laden insects. The difference in the demeanour of those that are setting out in search of prey or materials, and those that are returning home, is most notable; the former bustling along with a quick, eager step, looking this way and that, running first to one side of the path and then to the other, interchanging rapid communications with their comrades, and altogether brisk and busy. But when they have succeeded in their object, they march steadily homeward, with a preoccupied demeanour, taking no notice of passing events, and being apparently absorbed in the one task of depositing their burden in its proper place.
The observer will do well, while watching these insects, not to sit or stand upon or very near one of their roads, for the ants have no idea of being pushed out of the old paths, and are summary and fierce in their revenge on intruders.
As the ants pass and repass on their paths, they hold rapid communications with each other, mostly by means of their antennæ, which pat and stroke those of their gossip with surprising quickness, the whole transaction irresistibly reminding the observer of the Oriental method of conducting sales or barters by means of the hands. The antennæ, whose precise function is still rather obscure, are employed not only for actual communication with other ants, but to ascertain whether a companion has passed over a certain spot. This peculiar instinct is mostly exercised among trees. The ant roads seem even to extend themselves to the summit of trees, being generally confined to one side of the trunk, and ramifying to the very tips of the leaves, as may be seen by the means of a good field-glass. Ants may be seen passing and repassing upon the trees as briskly as upon the ground, and it is notable that when they get among the small branches, an ant will not go where another has preceded it, making itself aware of the circumstance by the tapping of the antennæ upon the bark.
The object of this tree-haunting habit is twofold, firstly that the individual may obtain food for itself, and secondly that it may bring in subsistence for the community. Its own nourishment is chiefly obtained from the aphides which swarm on many trees, and which have the power of exuding a saccharine fluid from a pair of minute tubes near the extremity of the body. When the aphides are very plentiful, the sweet juice falls on the leaves, and is popularly known under the name of honey-dew. Both bees and ants are fond of honey-dew, which the former insect licks from the leaves with its brush-like tongue, the latter taking a more direct course and lapping it as it exudes from the tubes. While on the leaves, the ants are more than usually combative, and if the hand be placed near them, will tuck their tails under them, sit up like dogs begging, and flourish their antennæ in a manner which they doubtlessly think well adapted to frighten the disturbers of their peace. When, however, the angry insect finds that menace is ineffectual, and that it cannot alarm the foe, it settles the matter by dropping to the ground. If an ant-infested tree be suddenly struck with a stick, the ants tumble down in all directions, falling quite unconcernedly from a height of fourteen or fifteen feet, and rattling like hail upon the dried leaves at the foot of' the tree. When they reach the ground, they lie motionless for a moment, and then pick themselves up and run away as if nothing were the matter.
Though they instinctively spare the aphides, (an instinct which every gardener cannot but wish to be suppressed,) they are terrible foes to other insects, seizing them and dragging them into their nests most zealously. I once saw an unfortunate daddy long-legs (Tipula) caught in a gust of wind and blown upon a nest of the wood ant. No sooner had the ill-fated insect touched the nest, than it was surrounded by a host of ants, its legs seized by twenty pairs of jaws, its wings dragged from their joints, and the still struggling body pushed and pulled along until it was finally dragged into the recesses of the nest. I have often tried the experiment of putting a large fly in their path, and always found their mode of procedure to be the same. They cluster round the fallen insect like flies round a lump of sugar, they seize upon its legs, they pull off its wings in a moment and run away with the severed organs, four or five others following the fortunate captor, just like a brood of chickens after the one that has been lucky enough to pick up a piece of bread. They then attack the wingless body with ruthless violence, biting at it like a hungry cat at a slice of meat, or perhaps more like a herd of wolves at their prey: they soon deprive it of life, haul it to the nest, drag it up the side, and literally tumble it into one of the holes.