Insect Architecture

by James Rennie

Nest of Myrapetra.

[The accompanying illustration shows this remarkable nest, both as it appears externally, and when divided vertically.

The material is probably the dung of the Capincha, an animal allied to the guinea-pig and the agouti. The natives, at all events, state that such is the case, and the aspect of the nest as seen through a magnifying glass carries out this assertion. The nest is hung to a branch, and is seldom more than four feet from the ground. The insect is a very little one in comparison with the size of the nest, which is sixteen inches in length, and twelve in width. The largest specimens of this insect are only one third of an inch long, while the generality scarcely exceed a quarter of an inch. Its colour is brown.

In the section is shown the very peculiar shape of the combs. At the upper part is seen the globular centre, surrounded with a comb that completely encircles it. Other combs follow in order, but are less curved as they approach the bottom of the nest. The insects obtain admission to the several tiers by means of apertures which are left between the extremities of the comb and the wall of the nest. The combs are made of the same material as the outer wall, but are very thin and paper-like. This nest may be seen in the British Museum.]

It would seem that the nest described by Mr. White agrees with that of a wasp termed Chiguana by Azara (or Lecheguana), and is very different to the slight papery nest of the Polistes Lecheguana of Latreille. We may add that M. Auguste de St. Hilaire speaks of two species of wasps remarkable for storing honey in South America; the honey of one is white, of the other reddish. That the habits of these honey-wasps must differ considerably from those of any of our European species we may at once admit; perhaps in some points of their economy these insects may approach the bee.

[In the same country as is inhabited by the Myrapetra, and in much the same localities, is sometimes found the nest of another honey-making wasp, called Nectarinia analis, a small and plainly-clad insect. It is hung to the branches of low trees and underwood, and often includes both twigs and leaves in its structure. The combs of this insect are greatly curved, in order to suit the shape of the general covering, but are not arranged with that beautiful regularity which distinguishes those of the Myrapetra. A specimen of this nest may be seen in the British Museum, and as the outer covering has been partially taken away, the observer will be enabled to note the general form of the combs and the structure of the cells.

In the accompanying illustration are shown the habitations of two remarkable insects, both belonging to the Hymenoptera. Indeed, the greater number of pensile nests made by insects are formed by members of this important order; and, if we were to exclude all the wasps, bees, and ants, we should find that we had excluded about ninety per cent. of the pensile architects.

The left-hand figure represents a nest made by a species of Polybia, inhabiting Brazil. It is made of a papery kind of substance, of rather slight texture, and is fixed to the stalk of a reed. The outside of the nest is seen to be marked with a series of horizontal ribs. These show the progressive stages of the nest, each rib marking a layer of paper as it was spread by the insect builder. The combs extend throughout the entire nest, the largest occupying the centre, and the smallest the ends. Each comb is firmly supported by a footstalk, which is fixed, not to the upper tier of cells, as is the case with the British wasps, but to the reed on which the nest is built.

Other species of Polybia build nests different in shape and arrangement, though still of the pensile character. One species builds a nearly globular nest, made in a rather curious manner. Carrying out still farther the principle on which the cardboard wasp enlarges its nest, the Polybia entirely covers the outer wall with cells, and then makes a new wall over them. When a nest has reached a tolerable size, it is composed of a whole series of concentric combs, the roof of each having been originally the outer wall of the nest. There are in the British Museum some admirable specimens of these nests, in some of which the process of enlargement can be very clearly traced. Patches of new cells are seen upon the external covering, while a few breaches in the structure show the concentric combs.