Popular Science Monthly/Volume 48/December 1895/Insects' Eggs
By M. V. BRANDICOURT.
JOHANNES SWAMMERDAM, a Dutch naturalist, who was the first to examine insects with a microscope, and whose investigations were published in 1757, gave some curious details concerning the eggs of insects. "Some are oblong," he said, "others ovoid or round. There are also angular, pyramidal, striated, and granular eggs, etc. They are no less various as to colors, and we find them white, yellow, red, blue, green, and pied with different colors so singularly combined that it is almost impossible to describe them exactly. In consistence, some are soft, others hard; some membranous, others covered with a coat like parchment or with a real eggshell; some are covered with a kind of froth, others with hairs."
Swammerdam described with many details the eggs of the Nepa cendrea, a little fresh-water hemipter, which he called the water scorpion (Fig. 10). They are yellow and nearly of the same shape as the seed of the blessed thistle, slightly elongated, and rounded at the lower end. On the upper part they are provided with seven or eight slender branches, or hard threads, of which the point is red and the middle whitish. These appendages or threads, arranged in a circle around the circumference of the summit of each egg, form a kind of open egg cup, which receives the end of the next egg in its cavity. Thus these appendages of the first egg hold the lower end of the second, and so on.
The eggs of the Lepidoptera, have considerable resemblance to the seeds of plants (Figs. 1, 3, 3, 4). "Those of the larger and smaller cabbage butterflies have the shape of a pyramid, of a height three or four times the diameter of the base, and the base is stuck to a leaf. The eggs are usually formed by eight rounded ribs, separated by flutings running from the summit to the larger end. On each of these sides may be seen an infinite number of flutings parallel to the base. The eggs of the great tortoise butterfly are nearly spherical, and are smaller in diameter at the base, or the part by which they are attached to the plant, than at the summit, whence eight equally distant crests descend along the body of the egg, forming ribs which diminish imperceptibly in height and disappear before reaching the end."
These eggs resemble those of a night moth which attaches its eggs to the branches of trees. They hold there with such strength that they leave a scar on the bark, and even interfere with the nutrition of the branch. They are remarkable for being shaped like the stones that are cut for the construction of arches, and, "being larger at the summit than at the base, so that they join exactly, they arrange themselves in an arcade."
Some butterflies have eggs of very elegant shape, resembling a kind of little knob, fluted and girt with a small purple circular band.
The eggs of the dragon fly are elongated; at the upper end are a kind of flowerets like those of the louse nit. The gnat's
Figs. 1 and 2, eggs of the large and of the small cabbage Pieris; Fig. 3, egg of the Tristan butterfly (Papillo hyperantus); Fig. 4, egg of the admiral (Vanessa atalanta); Figs. 5 and 6, eggs of Polyommatus; Figs. 7 and 8, eggs of Dicranitra vinula, profile and front views; Fig. 9, egg of Pygaera tricephala; Fig. 10, egg of water scorpion (after Swammerdam); Fig. 11, egg of gnat; Fig. 12. nit of the louse (after Swammerdam, greatly magnified).
egg is like a skittle, the larger end of which is rounded, while the other end terminates in a short neck, like those of some liquor flasks (Fig. 11). The eggs of the ephemera can be observed only under the microscope, on black or blue paper. They are plano-convex and oblong. The membrane that envelops them has a nebulous appearance under the microscope. The eggs are white, like the inner coating of thin shell.
The Euryanthus horribilis of New Guinea, on the other hand, an orthopter of the singular tribe of the phasmids, which is twelve or fifteen centimetres in length, lays eggs, it is said, as large as those of a humming bird.
The blowfly has an oblong, angular egg, with lozenge-shaped compartments forming a kind of network. They are very white and composed of two distinct envelopes, of which the outer one is a real shell like that of a hen's egg, and breaks as easily.
The egg of the ant is uniform, smooth, tight and bright, without any division. When the larva has come from it, only a very thin membrane is left, which rolls up and is reduced to an imperceptible point; and even if the egg does not hatch, it is still so small as to escape the eyes. This is why these eggs are so little known, for what is commonly and improperly called the egg is really the larva, and is endowed with life and motion. These eggs, or rather these larvæ, of ants are very much sought after by barnyard fowl. An old woman of Paris gained a very comfortable income by selling them at the Jardin d'Acclimatation to feed the pheasants. She collected them in the woods of the suburbs, indifferent to the bites she received from the old ants. Her trade extended from June till the end of September. Ants' eggs are considered a choice dish in some countries. They are spread upon a slice of bread and butter, and sauces considered excellent are made with them. They are esteemed as a costly food in Siam, within the reach only of well-to-do people. They are the object of an important trade in some countries of northern Europe, where they are cooked in boiling water, and yield a kind of vinegar or formic acid.
The eggs of certain aquatic insects resembling noctonectæ (Corixo femorale and Corixo mannaria, Geoffroy, and Noctoneda Americana) are eaten in Mexico. They are usually found deposited on the reeds and rushes of the lakes, especially of Lake Tezcuco. The egg-laden reeds and rushes are cut, dried, and beaten over cloths, to detach the myriads of eggs which are fastened on them. The eggs are very carefully cleansed, and are, after that operation, winnowed, put up in sacks like flour, and sold as material for cakes. This novel aliment, which is called hantlé, and is really water-flea bread, is the object of considerable trade in the markets of Mexico. It has a pronounced fishy flavor, and was used by the natives prior to the conquest. The eggs of another species (Corixa esculenta), which resemble manna, are eaten in Egypt, and form an element of very choice dishes.
The eggs of insects resist considerable variations of temperature. The most rigorous cold of our winters is fatal to the eggs only of the most delicate species; and the eggs can likewise resist the most intense tropical heats.—Translated for the Popular Science Monthly from La Nature.