Homes Without Hands: Being a Description of the Habitations of Animals, Classed According to Their Principle of Construction - Page 88

The nest was found in a Guianian forest, near the River Berbice, suspended to a branch, which passed through a hole in the solid wall of the nest. In the actual specimen the branch is wanting; but in the illustration it has been restored, in order to show the manner in which the winged artificers suspended their wonderful home. As is always the case with pensile nests, the foundation is laid at the top, thus carrying out Dean Swift's suggestion for a new patent in architecture. A large quantity of clay is worked round the chosen branch, and made very strong, in order to sustain the heavy weight which will be suspended from it. This clay foundation is wonderfully hard, though very brittle, this latter quality being probably due to the long residence in a room which is always kept warm and dry by artificial means. In the open air, and in the ever-damp, though hot atmosphere of tropical America, the clay would probably be much tougher, without losing the necessary hardness.

Mud Wasp.

The combs are not flat, like those of an ordinary wasp-nest, but are very much curved, so that when the nest is laid open they almost follow the curve of the walls. This peculiar form of the comb is shown in the illustration. The cells are not very large, scarcely equaling the worker cells of the common burrowing wasp of England.

One of the most remarkable points in the construction of this nest is the entrance. In pensile nests, the insect usually forms the opening below, so that it may be sheltered from the wind and rain. Moreover, it is usually of small dimensions, evidently in order to prevent the inroads of parasitic insects and other foes, and to give the sentinels a small gateway to defend. But the particular Wasp which built this remarkable nest seems to have set every rule at defiance, and to have shown an entire contempt of foes and indifference to rain.

As may be seen by reference to the illustration, the entrance is extremely long, though not wide, and extends through nearly the length of the nest, so that the edges of the combs can be seen by looking into the aperture. The edges of the entrance are rounded, so that the outer edge is wider than the inner; but it is still sufficiently wide to allow the little finger of a man's hand to be passed into the interior, while its length is so great that forty or fifty insects might enter or leave the nest together.

THE remarkable fact has already been mentioned that two species of Wasp will inhabit the same nest, and amicably work at the same edifice. Entomologists have long been aware that two species of Ant will dwell in the same nest, and live upon friendly terms, although the association of the working part of the community is not voluntary, but compulsory.

The Ant which employs enforced labor is called the Amazon Ant (Polyergus rufescens), and is tolerably common on the Continent. This insect is not furnished with jaws which are capable of performing the work that usually falls to the lot of the neuters, but the same length and sharpness of the mandibles which unfit the insect for work, render it eminently capable of warfare. When, therefore, a colony of the Amazon Ants is about to establish itself, the insects form themselves into an army, and set off on a slave-hunting expedition.

There are at least two species of Ant which act as servants to the Amazon Ants, the one being named Formica fusca, and the other Formica cunicularia; and to the nests of one or other of these insects the Amazons direct their march.

As soon as they reach the nest, they penetrate into all its recesses, in spite of opposition, and search every corner for their spoil. This consists solely of the pupæ which will afterward be developed into neuters, and vast numbers of the unconscious young are carried off in the jaws of the conquerors. The rightful owners and relatives of the captured young can not resist the enemy, as their shorter though more generally useful jaws are unable to contend with the long and sharply-pointed weapons of their foes.

After the marauding army has returned, the living spoils are carefully deposited in the nest, where they are speedily hatched into perfect insects of the worker class, and immediately take on themselves the labors of the nest, just as they would have done in their own home. The Amazon Ant seems to be utterly incapable of work; and in one notable instance, when a number of them were confined in a glass case, together with some pupæ, they were not only unable to rear the young, but could not even feed themselves, so that the greater number died from hunger. By way of experiment, a single specimen of the slave Ant (Formica fusca) was introduced into the case, when the state of affairs was at once altered. The tiny creature undertook the whole care of the family, fed the still living Amazon Ants, and took charge of the pupæ until they were developed into perfect insects.

Some writers have enlarged upon the hard lot of the slave Ants, imagining their servitude to be as distasteful to them as it is sometimes made to human slaves. Mr. Westwood, however, points out very clearly that any compassion bestowed upon them is wasted, and that the lot of the "helots"—if they may be so called—is precisely that for which they were made. The labors which the little creatures undertake are not arbitrarily forced upon them by the dread of punishment, but are urged upon them by the instincts implanted within them. They would have worked in precisely the same manner, and with exactly the same assiduity, in their own nests as in that of their captors, and the labors are undertaken as willingly in the one case as in the other.

They find themselves perfectly at home, and are in every respect on a par with their so-called masters. In point of fact, however, the real masters in the nest are the slaves, for upon them the Amazons are dependent from their earliest days to the end of their life, and without them the entire community would perish. The slaves have no other home but that to which they have been brought, and are no more to be pitied than are dogs, cattle, and other domestic animals that never have freedom. Indeed, none but solitary animals can be free even in the wild state, for they are held in absolute servitude by the leaders of the herds, and, if they dare to disobey, are summarily punished.

As the slaves are always neuters, it is necessary that fresh importations should be made as fast as the demand for workers exceeds the supply; and it is really a wonderful thing that the Amazon Ants should always select the pupæ which will afterward be developed into neuters, and never take those from which males or females will issue.

The Amazon of the Continent is not the only Ant which enslaves the neuters of another species, for in different parts of the world several species of Ants have been observed which seize upon workers belonging to other nests, and bring them to do the work of the home. A Brazilian species (Myrmica paleata) has been observed to act in this manner.

In the accompanying illustration are shown two remarkable nests, made by insects of the same genus, which have been placed side by side in order to show the different manner in which cells are arranged by insects which are closely allied to each other.

Nests. Polistes aterrima, etc.

The smaller, though more conspicuous nest, is formed by an insect which is called Polistes aterrima, a name which is very appropriate to the creature, inasmuch as the generic title signifies a builder, or the founder of a city, and the specific name signifies intense blackness, and is given to the insect on account of its color. In general shape the insect resembles other species of its genus, but is rather larger than the generality of its kin, and is conspicuous for its deep black color.

The method of nidification which this species adopts is very peculiar. The cells are formed with beautiful regularity, but are arranged in a very curious fashion. They are placed with their mouths downward, as is frequently the custom with the cells of hymenoptera, but are not quite perpendicular, inclining alternately to either side. Each cell is set rather lower than its predecessor, so that the general effect is very peculiar, and gives to the cell group a character which renders it at once recognizable.

THE second nest which is represented in the same illustration is scarcely so striking in appearance as the preceding, but is equally interesting, and to many minds more so, because the architect is at present unknown, and there is some little mystery about the edifice. That it is the work of a Polistes is evident enough from the character of the cells, but it is not made by any of the numerous species whose nests are already in European collections.

The color of the combs is a rather sombre brown, so that at a little distance the whole group would easily escape notice, especially if it were buried in the depths of the forest, as is the case with many similar nests. The cells are about the same size as those of the curious clay nest which has already been described, but they are undefended by any covering, and exposed to the weather.

It has been suggested by some observers that the combs might have been originally protected by an outer case, and that the case itself has been lost. The formation of the branch, however, from which the combs are hung, serves to militate against any such theory, as the twigs project so far that they must have been enveloped by the covering if it ever existed, while upon them there is no trace of any such material as that of which the nest is made. The inference is, therefore, that they were never intended to be protected by a cover, but that they were intentionally exposed to the air, as is the case with the habitations of Polistes and several allied insects, whose homes will shortly be described.

One of the most curious points in the construction of this nest is the manner in which it is suspended to the branch. As is shown in the illustration, the combs are comparatively narrow at the point of attachment, and gradually increase in width, so that their weight, when filled with the young brood, must be considerable, and the strain on the upper part of the comb very great. The manner in which the insect has met this difficulty is really wonderful. It has not made the upper part of the comb to consist of a solid mass, as is the case with the clay nest which has just been described, but has utilized almost every portion of the comb from the top to the bottom. But, in order to obtain the needful strength, the upper part is constructed after a manner that is widely different from that which prevails upon the lower and wider portion of the comb.

If one of the combs were broken across, the lower half would much resemble, except in color, the nest of an ordinary wasp, except that the cells are smaller, and the material stronger; but toward the top the partitions between the cells become thicker, and, in consequence, the cells are fewer. This increased strength is chiefly found in the partitions which run perpendicularly, and which are so thick that the hexagonal form of the cells becomes obscured, the great object being, not the exact shape of the cells, but their ability to bear the weight of the comb below.

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