An Insect emerges from the egg as a grub, or caterpillar. As such It enters upon a period of active existence, when its chief business In life is the assimilation of nourishment; and not until It has lain dormant for a while as a pupa or chrysalis does it assume the perfect, winged state. These middle stages of an Insect's life the grub and pupa may be regarded as its babyhood. Moreover, the insect is almost always an orphan, its parents having expired soon after t e egg was deposited; so that the young Insect must depend mainly for protection upon the seclusion of some kind of nursery, formed either by its own early efforts, or by the instinctive labors of Its parents. These retreats range from mere tunnels beneath the surface of the ground to wonderfully wrought structures formed from a special material manufactured by the Insects themselves. To search for and to examine these varied nests and nurseries Is one of the most pleasant country pastimes. We will pass over the burrowers In the soil, and the tunnelers in wood, both rotten and sound. A word may be said, however, respecting those Insects which pr.ss their babyhood within fruit and vegetables, often much to the annoyance and loss of the horlcultur-1st. We may take for an example the well-known pest, the codling moth an Insect which attacks all the best kinds of apples. The moth lays its eggs singly upon the very young apples one to each fruit. As soon as the grub hatches, it tunnels Inward and makes for the core, upon which It chiefly feeds. Many of the apples known as "windfalls" have been attacked by these grubs, and the pests may be discovered merely by splitting the fruit open with a knife. If undisturbed, the little caterpillar eventually makes its way out of the apple, and concealing Itself in a cranny of the bark, changes to a chrysalis. This insect is troublesome not only in the United States, but wherever apples are grown. In Tasmania it is especially dreaded, and the legislature has passed an act for its repression. The grubs of other small moths actually mine between the outer skins of leaves, subsisting upon the green tissue, which they gnaw away. That these insects are exceedingly minute is manifest by the fact that the leaves within which they feed and find shelter are not much thicker than stout paper. Many leaves are thus attacked, the various kinds of bramble being specially liable. Sometimes the workings of the caterpillars are seen In long, tortuous galleries; at others, the inner tissue is eaten away over considerable areas, and blister-like blotches result. We may now pass to those Insects which gain shelter by means of secretions from their own bodies. Good examples are the so-called "spit" or "cuckoo-spit" Insects. The Immature Insects form strange patches of frothy moisture upon leaves and twigs; and these are virtually liquid nests. Within, the owner sucks the juices of the plant upon which it finds Itself, inserting its tiny beak beneath the bark of the stem. Ultimately, when it becomes adult, it abandons its frothy home, and lives a dry and active life as a fully developed "hopper." Scientifically speaking, it belongs to the great order Homoptera. Many of its near relatives, especially those of tropical countries, have the power of secreting a waxy substance, thus supplying their persons with a protective disguise. Something of the kind is seen in the case of the well-known and much-dreaded "woolly aphis," a pest which does so much damage to apple trees. There can be little doubt that these secretions, whatever their character, are a provision of Nature whereby the Insects are hidden from the sharp eyes of birds and Insectivorous creatures in general. We now come to case-making insects, which form a small but interesting group. The best known, perhaps, are the aquatic grubs of the caddis flies. As soon as the young larva emerges from the egg, it sets about collecting material for its caseor, in other words, the nursery in which it may lie secure from the attacks of other water creatures. Different species of caddis flies select different materials, though what governs their choice is not always possible to say, though at times it is obvious that they take whatever material is most abundant upon their particular stream bottom. Some choose small fragments of stick or reed, others make use of tiny stones, while still others gather together small shells, caring not whether their rightful owners have, or have not, abandoned them. Eventually, when the period of feeding is complete, the grubs close the entrance of their cases, and change to pupae therein. But caddis flies are not the only insects which form protective cases. The habit is shared by certain moths, belonging to several families. The tiny caterpillar of the "cloth moth," for example, builds for itself a cylindrical case from fragments of the cloih upon which it feeds, as may be observedalas! too frequentlywithout crossing the threshold of one's own home. The caterpillars of other moths, outdoor species this time, make their cases of lengths of grass, stick, or reeds, fixing the material together with a silk lining. Of some such moths, the females are wingless, and remain in their cases throughout life, actually depositing their eggs therein. Thus the old nursery of the mother becomes a place of protection for the eggs until they hatch in the following season. Among moths, too, we find that many caterpillars which dwell habitually in company construct a common nest, or tent, for the benefit of the community. Such is the well-known American tent caterpillar, the moth being responsible for a good deal of damage in orchards and gardens. The tents are really nests of silk spun among leaves and twigs. In them the caterpillars dwell when young, and to them they resort for shelter in rainy weather, and at night, even when they are older grown. Allied species, which pass through the winter in the caterpillar state, construct hibernacu-lums, or winter sleeping places. These are often conspicuous among the branches during the cold months of the year. If torn open, they reveal a surprising thickness of spun silk, forming a dense, non-conductive wall. At the center of the mass lie from thirty to fifty tightly-packed caterpillars, waiting for the return of the warm weather, when they will resume their feeding. Up to the present, we have seen only how imma' ture insects provide nests and nurseries for themselves. But not infrequently both food and a safe retreat are provided by the parent at the time of egg-laying. At a few such cases we may now glance, taking first a typical species of burying beetle. In the course of a country ramble one often comes upon a dead bird, mouse, or some such carcass. On turning it over with a stick, several burying beetles may usually be discovered at work. Their method of procedure is as follows: The dead body being found, the female deposits her eggs upon it. She appears to be endowed with an instinct which tells her just how many hungry grubs the particular carcass will support, and she lays her eggs accordingly. Then both the male and the female beetle commence the interment. They scoop away the earth from beneath the body, which gradually sinks into the ground. In the case of a rabbit or a rat", or any such large animal, many pairs of beetles combine their labors; and when the ground beneath is soft, the Interment is often completed in a surprisingly short space of time. Thus when the young grubs hatch from the eggs they not only find themselves surrounded by abundant food, but are able to consume it secure from the attacks of birds and other grub-eating creatures, to which they would be exposed upon the surface of the ground. Incidentally, it is worth noting that these Insects are capital scavengers, for they hide away rotting matter in the best of all deodorizers. Mother Earth. In like manner a vast number of beetles act as scavengers, and at the same time provide food for their offspring, by burying the droppings of animals. The scarab, or sacred beetle of the Egyptians, is one of these; but hundreds of allied species, in almost every country of the globe, have similar habits. They make balls of the refuse matter, lay an egg in the center of each, and then roll the balls about in the sun to harden. Finally, a hole is bored in the ground, and the ball is burled therein. When the grubs hatch, they feed upon the manure; thus not only sustaining themselves, but mingling the valuable nitrogenous matter with the soil. IBut of all Insects, the most careful parents, the most accomplished nest builders, are certainly the bees and wasps. Both groups of Insects are subdivided, according to their habits, into social and solitary species. The latter know nothing of joint labor, each female constructing and provisioning a few cells, or nurseries, in which to place her eggs; the former dwell together in colonies and build elaborate nests. But in all species the instinct of nest building is highly developed, while the material employed varies as much as the manner in which it is shaped into the required form. A typical solitary nest-builder is the leaf-cutter bee, of which a number of species have been described, each using a different kind of leaf, or the petals of flowers. The species to which we will turn our attention employs the rose leaf for its architecture. The Insect first searches for a rotten beam or fence, into which she tunnels, readily chipping away the soft wood with her powerful jaws. She then repairs to a rose tree, and cuts from a leaf an oblong portion. This she does as quickly as an experienced tailor cuts cloth, and with equal accuracy. The portion of leaf is then conveyed to the tunnel, one or more pauses being made by the bee for rest should the distance be great. The Insect now carries the portion of leaf to the extremity of her tunnel, treads it into place, and immediately returns for a second piece. The process is repeated until the bee is satisfied that the requisite number (usually seven) of pieces has been cut and put into place in the form of a thimble-shaped cell. This cell is then partially filled with a mixture of pollen and honey, upon the summit of which r.n egg is laid. Four circular pieces of rose leaf are then cut by the bee, and pressed down to form a cover for the cell; and when one cell is complete, the insect goes on to construct others until her tunnel is filled. Each grub, when it hatches, finds Itself in a snug little nursery, secure from enemies, and supplied with the exact amount of food requisite for its needs. When it has eaten what the cell contains, it will be ready to spin its cocoon and assume its pupa form, and will require no more nourishment until it emerges as a mature winged Insect. This is merely a typical example of a solitary Hymenopteron. Innumerable other species abound in summer, and each has its own way of providing nurseries for its progeny. Some small kinds of solitary wast."3 build with mud in holes, and if they can find a hole ready made, they willingly make use of it. In most museums we may see specimens of such nests fitted into the hole in a reel of cotton, a pipe stem, or some such homely article. But if the reader will take the trouble to examine discarded domestic objects of this kind which have been lying long in an outhouse, or upon a garden heap, he is quite likely to find these wasps' nests for himself, and may have the satisfaction of hatching out the wasps in due season. It is, however, among the social wasps that we find the most wonderful builders; we find, too, a most remarkable physiological difference between the insects themselves. Solitary wasps and' bees are merely divided into two sexesmales and females; but among social species we find not only males and females, but also a large percentage of Imperfect females, linown as workers. These workers, although they are capable of laying eggs, and do at times lay them, are said invariably to produce males, or drones. They of course bear no direct part in the perpetuation of the species, but they constitute a powerful labor factor in the Insect community of which they are members, and it is owing to their ceaseless labors that the marvelous nests, consisting of thousands of cells, are built up and repaired. Much has been written respecting the habits of social bees, so that we may devote our remaining space to a brief consideration of social wasps as typical of communal nest builders in general. Unlike bees, many kinds of which pass the winter in their nests, sustaining life upon the provisions which they have collected during the summer, wasps succumb before the increasing cold of autumn. But from this merciless scourge of mortality a few wasps escape. These are the "queens" of the next season. They pass the winter in some warm cranny, and when the spring arrives, each one comes forth from its hiding place, and seeks a suitable position for the nest that is to be. This found, the queen repairs to a fence or tree trunk, and with her jaws rasps off a bundle of wood fiber which, when moistened with saliva and kneaded, forms the paper-like substance of which the nest is entirely constructed. For just as bees have, so to speak. Invented a special nest-building material which we call wax, so wasps have acquired the habit of preparing for the same purpose a rough, but very durable paper. The queen-mother lays the foundation of the city with her own handsor, rather, with her own jaws. She attaches a sort of stalk of wood paper to a chosen support. This may be the branch of a tree, a root in a cavity below the ground, or a beam in a garden shed. The choice of locality varies with the species of wasp. But the stalk prepared, the queen proceeds to construct a few shallow cells, in each of which she lays an egg. After *lns she continues to form more cells, and to lay more eggs; and ere long she has to feed the young grubs which have hatched from the first batch laid, so that her time is fully occupied. Soon, however, some of the grubs turn to pupae, and the pupae to perfect waspsworker wasps, which take over the labor of the young colony. Thus, the city grows rapidly, until the vast nest, with its thousands of cells, comes into being. In conclusion, special attention may be called to the durability of the wood-paper manufactured by the wasps. Even in tlie case of the frailer nests built in the open by tree wasps, the power to withstand the effect of rain is very great; while the nests of the tropical species seem designed to resist the heaviest downpours. Such a nest is shown in the accompanying photograph. It was cut from an orange tree in Brazil, and its smooth exterior resembles thick cardboard.
This article was originally published with the title "The Nests and Nurseries of Insects" in Scientific American 97, 22, 396-398 (November 1907)