Ant-lion, in zoology, an insect so called from its devouring great numbers of ants. It is the caterpillar or worm of a fly much resembling the libelle or dragon-fly; and feeds chiefly upon ants, from which property it derives its name.

It is somewhat of the nature of the spider in its way of taking its prey, its manner of spinning, and the figure and softness of its body. It has, in its general figure, somewhat of the appearance of the millepes or wood-louse, so that some have mistaken it at first sight for that animal. It is of a dirty greyish colour, marked with some black spots; and these are also composed of many points when viewed with a microscope, which make it resemble a hedge-hog or porcupine. Its body is composed of several rings, and has hence a wrinkled look. It has six legs, four are joined to the breast, and the other two to a longer part, which may be taken for its neck. Its head is small and flat, and it has two remarkable horns: these are about a sixth part of an inch long, and as thick as a hair: they are hard, hollow, and hooked at the end like the claws of a cat. At the origin of each of these horns, it has a clear and bright black eye, which sees very distinctly, and gives the creature notice to escape on sight of the smallest object.—This creature is not able to hunt after its prey, nor to destroy large insects; it can only draw into its snare such as come near its habitation, and of these very few are such as he can manage: all the winged kind are able to escape by flight; and the beetle kinds, and others that have hard flecks upon their bodies, are of no use to him, as his horns cannot pierce them. The smallness of the ant, and the want of wings in the neuters, make them the destined prey of this devourer. The manner in which he catches his prey is as follows.

He usually encamps under an old wall, that he may be sheltered from the injuries of the weather; and he always chooses a place where the soil is composed of a fine dry sand. In this he makes a pit of the shape of a funnel, or an inverted hollow cone. If he intends the pit to be but small, he thrusts down his hinder part into the sand, and by degrees plunges himself backwards into it; and when he has got to a certain depth, he tosses out the loose sand which has run down with his head, artfully throwing it off beyond the edges of his pit. Thus he lies at the bottom of a small hollow, which is widest at the top, and comes sloping down to his body.

But if he is to make a larger pit, more pains are required to bring it to perfection. He first traces, in the surface of the sand, a large circle, which is the erected base or mouth of the pit he is to make in form of an inverted cone. He then buries himself in the sand near the edge of this circle, and carefully throws up the sand above him, with his head tossing it out beyond the circumference of the circle. Thus he continues his work, running down backwards in a spiral line all the way, and carefully throwing off the sand from above him, till he is come to the place of his rest, which is the point or reverted apex of the hollow cone he has formed by his passage. The length of his neck, and the flatness of his head, gives him a power of using the whole as a spade, and throwing off the sand with great ease; and his strength in this part is so great, that he is able to throw off a quantity of it to six inches distance. This is a power he exerts oftener, however, in throwing away the remains of the animals he has fed upon, that his den may not become frightful to others of the same species, by seeing their fellow carcasses about it.

When he has finished his pit, he buries himself at the bottom of it among the sand, leaving no part above ground but the tips of his two horns, which he expands to the two sides of the pit. In this condition lie lies and waits for his prey, and never comes up afterwards. When an ant, or any other such creature, chances to walk over the edges of his pit, its feet throw down a little of the sand, which naturally running down to the bottom of the pit, gives the enemy notice of his prey; he then tosses up the sand which covers his head, to bury the ant, and bring him down with its returning force to the bottom; and as one such attempt cannot be sufficient to prevent the ant's escape, he throws more and more sand upon him, till he by degrees brings him down. All the endeavours of the ant to escape, when once it is within the verge of the pit, are in vain; for, as it attempts to climb, the sand runs away from under its feet, and it sinks the lower for every attempt. This motion of the sand also informs the enemy where it is, and directs him to throw up more sand in the right place; which it does, till the poor ant falls to the bottom between its horns. It then plunges the points deep into the ant's body; and having sucked all the juice out of the prey, it throws out the empty skin as far from the hole as it can. This done, it mounts up the edges of its pit, and if it has suffered any injury, repairs it with great care, and immediately buries itself again in the centre, to wait for another meal. The horns of this creature are its only organs for receiving nourishment; it never brings any animal which it has seized near to its head, but always holds it at the tip of the horns. They therefore plainly serve as syringes, to draw into its stomach the juices of the bodies of the insects it feeds upon; neither is there any mouth or trunk, or any other organ to be discovered about its head, which could serve to the purpose of eating; the head seeming only intended for throwing away the sand in forming the pit. The horns of this animal being so necessary to its life, nature has provided for the restoring them in case of accidents; and, if cut off, they are found to grow again.

The food this creature procures by its pit can be but little; and as it has no power of catching its prey any other way, its motion being only backwards, and that slowly, and by small spaces at a time, some people have believed its catching now and then an ant by this means was rather for diversion than hunger. But tho' the formica-leo will live a long time without food, and even pass through all its changes when shut up in a box, yet it is always ready to eat when food is offered it; it always appears starved and small when kept thus; and if a fly is given it in this hungry state, it will so suck out all its juices, that the shell remaining may be rubbed to powder between the fingers, while the body of the creature that has sucked it appears remarkably swelled and distended; so that it is plain that the juices of the prey are conveyed into the body of the creature; though it is not easy to see by what means, the horns not appearing to have any perforation.

When the formica-leo has lived a proper time in this state, it leaves its pit, and is only seen drawing lines and traces on the surface of the sand. After this it buries itself under the surface; and there incloses itself in a fine web, in which it is to pass its transformation into the winged state. This case is made of a sort of silk which the creature spins in the manner of the spider, and of a quantity of the grains of sand cemented together by a glutinous humour which flows from its pores. This case, however, would be too harsh and coarse for the body of the creature, and therefore it serves only for the outer covering to defend it from injuries; the creature spinning one of pure and incomparably fine silk, of a beautiful pearl colour, within it, which covers its whole body.

When the creature has lain some time in this case, it throws off its outer skin, with the eyes, the horns, and every other part necessary to its life before, and becomes an oblong nymph, in which a careful eye may trace the form of the fly into which it is to be transformed. There may be seen, through its transparent covering, new eyes, new horns, wings, and all the other parts of the animal in its perfect state. This nymph makes its way about half out of the shell, and remains in this condition, but without farther life or motion, till the perfect fly makes its way out at a slit in the back. In this last state it much resembles the libellae or dragon-flies common about our waters. The male couples with the female in this state only; and M. Poupard, to whom the world is obliged for this curious description, is of opinion that the females lay only one egg; but this is very different from the course of nature in the other animals of the same class.

When this insect forms its pit in a bed of pure sand, it is made and repaired with great ease; but where it meets with other substances among the sand, the labour becomes greatly the more embarrassing. If, for instance, when the creature has half formed its pit, and then comes to a stone of some moderate size, it does not desert the work for this, but goes on, intending to FORMING remove that impediment at last. When the pit is finished, the creature crawls backward up the side of the place where the stone is, and getting its backside under it, takes great pains and time to get it on a true poise, and then begins to crawl backward with it up the edge to the top of the pit, to get it out of the way. It is a very common thing to see a formica-leo in this manner labouring at a stone four times as big as its own body; and as it can only move backward, and the poise is hard to keep, especially up a slope of such crumbly matter as sand, which moulders away from under its feet, and necessarily alters the position of its body, the stone very frequently falls down when near the verge, and then it is sure to roll to the bottom. In this case the animal attacks it again in the same way, and often is not discouraged by five or six miscarriages of this kind; but, after all, attempts again, and at length gets it over the verge of the place. When it has done this, it does not leave it there, lest it should roll in again; but is always at the pains of pushing it farther on, till it has removed it to a necessary distance from the edge of the pit.

The common formica-leo moves only backward; but Mr Rouet has observed a species which moves forward in the common way of other animals, and makes no pit of this kind to entrap its prey, but seizes other insects by force.

FORMING is used for the act of giving being or birth to any thing.

The word is also simply used for giving the figure to any thing. The potter forms his vessels as he pleases. Geometry teaches how to form all kinds of figures.

It is likewise used for the producing of a thing; thus, the lineaments of the face began to be formed.

FORMING of a Siege, is the making lines of circumvallation to fortify the camp, and disposing things for the attack of a place in form.

They also say, to form a squadron or battalion; meaning, to range the soldiers in form of a squadron, &c.

FORMING the Line, is drawing up infantry, cavalry, and artillery, into line of battle. See LINE.

FORMING is also used in grammar, in speaking of certain tenses of verbs, which are made from others by a change of certain letters. The present tense is formed from the infinitive. Compound and derivative words also, and even all that have any etymology, are said to be formed.