Even when they concealed the mouth of the well under a layer of swept sand, my [[387]]various captives, large and small, were too assiduously watched by me to foil my curiosity. I know in every case the exact spot where the barrel of eggs lies. The time has come to inspect it.
The thing is easily discovered, an inch or an inch and a half down, with the point of a knife. Its shape varies a good deal in the different species, but the fundamental structure remains the same. It is always a sheath made of solidified foam, a similar foam to that of the nests of the Praying Mantis. Grains of sand stuck together give it a rough outer covering.
The mother has not actually made this coarse cover, which constitutes a defensive wall. The mineral wrapper results from the simple infiltration of the product, at first semifluid and viscous, that accompanies the emission of the eggs. The wall of the pocket absorbs it and, swiftly hardening, becomes a cemented scabbard, without the agency of any special labour on the insect’s part.
Inside, there is no foreign matter, nothing but foam and eggs. The latter occupy only the lower portion, where they are immersed in a frothy matrix and packed one on top [[388]]of the other, slantwise. The upper portion, which is larger in some cases than in others, consists solely of soft, yielding foam. Because of the part which it plays when the young larvæ come into existence, I shall call it the ascending-shaft. A final point worthy of observation is that all the sheaths are planted more or less vertically in the soil and end at the top almost level with the ground.
We will now describe specifically the layings which we find in the cages. That of Pachytylus cinerescens is a cylinder six centimetres long and eight millimetres wide.[1] The upper end, when it emerges above the ground, swells into a nipple. All the rest is of uniform thickness. The yellow-grey eggs are fusiform. Immersed in the froth and arranged slantwise, they occupy only about a sixth part of the total length. The rest of the structure is a fine, white, very powdery foam, soiled on the outside by grains of earth. The eggs are not many in number, about thirty; but the mother lays several batches.
That of P. nigrofasciatus is shaped like a slightly curved cylinder, rounded off at the [[389]]lower end and cut square at the upper end. Its dimensions are an inch to an inch and a half in length by a fifth of an inch in width. The eggs, about twenty in number, are orange-red, adorned with a pretty pattern of tiny spots. The frothy matrix in which they are contained is small in quantity; but above them there is a long column of very fine, transparent and porous foam.
The Blue-winged Locust (Œdipoda cærulescens) arranges her eggs in a sort of fat inverted comma. The lower portion contains the eggs in its gourd-shaped pocket. They also are few in number, some thirty at most, of a fairly bright orange-red, but unspotted. This receptable is crowned with a curved, conical cap of foam.
The lover of the mountain-tops, the Pedestrian Locust, adopts the same method as the Blue-winged Locust, the denizen of the plains. Her sheath too is shaped like a comma with the point turned upwards. The eggs, numbering about two dozen, are dark-russet and are strikingly ornamented with a delicate lacework of inwrought spots. You are quite surprised when you pass the magnifying-glass over this unexpected elegance. Beauty leaves its impress everywhere, even [[390]]in the humble covering of an unsightly Acridian incapable of flight.
The Italian Locust begins by enclosing her eggs in a keg and then, when on the point of sealing her receptacle, thinks better of it: something essential, the ascending-shaft, is lacking. At the upper end, at the point where it seems as if the barrel ought to finish and close, a sudden compression changes the course of the work, which is prolonged by the regulation foamy appendage. In this way, two storeys are obtained, clearly defined on the outside by a deep groove. The lower, which is oval in shape, contains the packet of eggs; the upper, tapering into the tail of a comma, consists of nothing but foam. The two communicate by an opening that remains more or less free.
The Locust’s art is not confined to these specimens of architecture. She knows how to construct other strong-boxes for her eggs; she can protect them with all kinds of edifices, some simple, others more ingenious, but all worthy of our attention. Those with which we are familiar are very few compared with those of which we are ignorant. No matter: what the cages reveal to us is sufficient to enlighten us as to the general form. It remains [[391]]for us to learn how the building—an egg-warehouse below, a foamy turret above—is constructed.