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 pratorum."

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

H H

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 harvest of nests, as well as of hay.

CHAPTER XXV.

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 OF 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 pupa-Parasites on vegetables— The 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

for instance, usurps the deserted hole of a water-shrew; and the humble-bee and wasp usually take advantage of the deserted burrow of some rat or mouse. In the account of the sociable weaver-bird, mention is also made of certain little green parrots, which are apt to take possession of the great nest, and use it for their own purpose. And in the last chapter an example was mentioned where a carder-bee established herself in the deserted nest of a wren, and so saved herself the trouble of fetching materials and building a dome.

BIRDS of various kinds are notorious parasites, the Cuckoos ranking as chief among them, inasmuch as they make no nest at all, but simply lay their eggs in the nests of other birds, and foist upon them a supposititious offspring, which occupies the entire nest and monopolises all the care of its foster-parents.

All Cuckoos, however, do not possess this habit; for some of the group build nests which are remarkable for their beauty, and tend their young as carefully as do any birds. The celebrated Honey-finders, for example, which are found in most hot portions of the globe, are notable for their skill in architecture. The nests of these birds are pensile, and not unlike those of the African weaver-birds, which have already been described. They are made of tough bark, torn into filaments, and are flask-like in shape, hung from the branches of trees, and having their entrance from below.

Then there is the well-known COW-BIRD of America (Coccygus Americanus), which is closely allied to the common cuckoo, and yet which builds its own nest, and rears its own young. Early in May," writes Wilson, "they begin to pair, when obstinate battles take place among the males. About the 10th of that month they commence building. The nest is usually fixed among the horizontal branches of an apple-tree; sometimes in a solitary thorn, crab, or cedar, in some retired part of the woods. It is constructed with little art, and scarcely any concavity, of small sticks and twigs, intermixed with green weeds and blossoms of the common maple. On this almost flat bed the eggs, usually three or four in number, are placed; these are of an uniform greenish blue colour, and of a size proportionate to that of the bird.

"While the female is sitting, the male is generally not very

far distant, and gives the alarm by his notes, when any person is approaching. The female sits so close, that you may almost reach her with your hand, and then precipitates herself to the ground, feigning lameness, fluttering, trailing her wings, and tumbling over, in the manner of the partridge, woodcock, and many other species. Both parents unite in providing food for the young."

In this narrative, two points are especially worthy of notice. In the first place, the egg of the Cow-bird is proportionate in size to the bird which laid it. Now, one of the most remarkable facts connected with the history of the common cuckoo is, that although the bird is as large as a small hawk, its egg is scarcely half as large as that of a thrush or blackbird, as indeed is needful for its admission into the nest of a hedge-sparrow or redstart.

Here, then, we have an example of a bird laying an egg which is extremely small in proportion to its own size, while in the apteryx or kiwi-kiwi of New Zealand, we have an example of a bird laying an egg which is absolutely gigantic in proportion to its own size. The apteryx is not a large bird, certainly not larger than a guinea fowl, and yet its egg looks like that of a swan, and weighs just one quarter as much as the bird which produced it. Thus it is evident that the dimensions of an egg afford no certain criterion respecting the size of the bird that laid it, and although a large bird usually lays a large egg, and a small bird lays a little one, the cases may be reversed, as in the instance just mentioned.

All naturalists are familiar with the gigantic egg laid by some bird unknown, and called by the provisional name of Epyornis, or "tall-bird." This egg makes that of the ostrich itself shrink into insignificance, for its lineal measurement is precisely double that of a large ostrich egg, and its cubic bulk is eight times as great. In fact, the æpyornis egg looks as gigantic by the side of an ostrich egg, as does an ostrich egg near that of a duck. It was therefore imagined that the æpyornis must be at least eight times as large as the ostrich, and a height of sixteen feet was attributed to the unknown bird.

Now, it is easy to work out this problem by the rule of three, and to give the result in figures; but when that result is compared with existing facts, it becomes startling. On paper, a