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 colour, the nest of an ordinary wasp, except that the cells are smaller, and the material stronger. But, towards 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.

The general effect of this modification can be easily imitated by taking an oblong piece of linen, rounding the corners, and plaiting one end, just as ladies gather in the upper part of an apron. The longitudinal folds will then represent the perpendicular partitions of the cells, and will show how strength is gained without needless expenditure of material. The strengthened partitions do not run quite perpendicularly, but are slightly irregular, just as would be the case with the folds of the linen if it were fastened to a branch by the plaited end, and suffered to hang loosely.

THE history of Social Insects would be incomplete without the mention of several British insects, which are plentiful enough, but which are scarcely known as well as they deserve. These are the creatures which are popularly known as CARDER BEES, because they prepare the materials for their nest in a manner

similar to that which is employed in carding cotton wool or heckling flax.

Several species of Carder Bee are known, all belonging to that familiar group of insects called Humble Bees. Among these, as among Humble Bees in general, there is a great variety of colour, so that the same species has been called by different names, even by skilled entomologists. For example, in Kirby's admirable monograph of British Bees, no less than seven varieties of the commonest species of Carder Bee (Bombus muscorum) are given as separate species.

That such mistakes should be made is no matter of surprise when we take into consideration the capriciousness with which the colours of this species are distributed among its members. Among the queen Bees, the abdomen is sometimes marked with rings of yellow, black and red, and is sometimes red at the base and tip and black in the middle. The worker has usually a yellowish abdomen, with one or two blackish bands, but in some cases the whole abdomen is black, except a small patch on the base and another at the tip. The male Bee has generally the abdomen coloured like the first-mentioned example of the worker, but sometimes it is wholly black, and in many cases it is black except the tip, which is dun. Indeed, these insects are so extremely variable, that the only method of determining their true arrangement is by taking a great number of nests, breeding the inmates, and subjecting them not only to careful external examination, but also to dissection of their internal anatomy.

The specific title "muscorum," i. e. " of the mosses," which is given to this Bee, is due to the material of which the nest is usually made. It was generally thought to be made exclusively of moss, but is in fact constructed of various substances, according to the locality. Mr. F. Smith mentions several instances where the Bees had made use of very singular and unexpected materials.

In one case, Bees were seen flying into a stable through the latticed window, collecting the little hairs that had fallen from the horses during the process of currying, making them up into bundles, and flying off with them. On being watched carefully, one of the Bees was seen to alight on some grass, not very far from the stable, and among the grass was found the nest, which

was composed entirely of horsehair. Unfortunately this remarkable nest was destroyed before it was completed.

"Another very interesting deviation from the usual economy of the moss-building Bees was observed by Dr. William Bell. During the summer of 1854, a robin built its nest in the porch of his cottage at Putney. Some time after this had been observed, a Humble Bee took possession of the nest, and adapted it to her own purpose. He was unfortunately unable to identify the species by capturing a specimen, the nest having been destroyed; but Dr. Bell saw the Bee on one occasion, and observed that it was black, with yellow bands, probably Bombus pra

torum."

Moss, however, is the favourite material of the Carder Bees, and wherever it can be obtained, they will use no other substance, though in places where it is scarce, or not to be found, they employ leaves, grass, or any other suitable material. Whatever may be the material, the Bee always takes great pains to disentangle the fibres, in order to be able to weave them in a systematic manner into the nest. This process is conducted by means of the legs, the Bee seizing the fibre with her fore-feet, and passing it under her body by means of the remaining pairs of legs, forming it, as she does so, into a small bundle which can be easily carried off.

The object of the moss and other substances is very simple. The Carder Bees do not build their nests, like those of many Humble Bees, beneath the surface of the ground, but upon it, choosing a spot where there is a slight hollow of an inch or two in depth. The moss is then woven so as to form a domed cover to the cells, this dome being of variable dimensions, according to the number of cells which it covers, but seldom reaching more than three or four inches in height above the ground. As in very rainy weather this mossy dome would not be waterproof, the insects line it with a very coarse, dark-coloured wax, similar to that of which the breeding cells are made.

The entrance to the nest is always at the bottom; for although the insects will sometimes make an opening at the top, they seem to do so merely for the purpose of admitting air and warmth, and never enter or leave the nest through it, closing it at night or in rainy weather. Generally, a kind of tunnel or arched entrance leads into the nest, like the passage into an

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Esquimaux snow-house, an edifice to which the moss-covered dome of the Carder Bee bears no small resemblance.

The best time to search for these Bees is in the hay-making season, when the scythemen often come upon them during their work; and a promise of some small reward for this or any other structure will probably produce a tolerable barvest of nests, as well as of hay.

CHAPTER XXIV.

PARASITIC NESTS.

Various Parasites-Parasitic Birds-The CUCKOO and its kin-The Cow BIRD and its nest-Size of its egg-Comparison between the Cuckoo and the ApteryxThe EPYORNIS-The BLUE-FACED HONEY-EATER OF BATIKIN-General habits of the bird-Singular mode of nesting-The SPARROW-HAWK and its parasitic habits—The KESTREL, its quarrel with a Magpie-The PURPLE GRAKLE or CROW BLACKBIRD-Its curious alliance with the Osprey-Wilson's account of the two birds-The SPARROW as a parasite-Curious behaviour of the STORK-Parasitic Insects The ICHNEUMON FLIES-The parasite of the CABBAGE CATERPILLAR --Its numbers and mode of making its habitation-Trap-doors of the cells-The Australian Cocoon and its parasites-The OAK-EGGER MOTH, its cocoons and enemies-The PUSS MOTH-Its remarkable cocoon-Powerful jaws of the parasite-RUBY-TAILED FLIES and their victims-Modes of usurpation-The CUCKOO FLIES or Tachina-Parasites within pupae-Parasites on vegetablesThe GALL FLIES and their home-British Galls, their shapes, structures, and authors-Foreign Galls, and their uses.

WE now pass to another branch of this inexhaustible subject, and come to those creatures that are indebted to other beings for their homes. In some cases, the habitation is simply usurped from the rightful proprietors, who are either driven out by main force or are ousted by gradual encroachment. In other cases, the deserted tenement of one animal is seized upon by another, which either inhabits it at once, or makes a few alterations, and so converts it to its own purposes. In many instances, however, the habitation of the parasite is found within the animal itself; and in some cases the entire body forms the habitation of the parasite.

Several examples of the first description of parasites have already been given under other headings. For instance, where the puffin invades the rabbit-burrows, and drives out the rabbits by dint of courage and a powerful beak; or where the Coquimbo owl and rattlesnake take possession of the homes which had been excavated by the prairie dog. Examples of the second description of parasites have also been given. The kingfisher,