The insect that infests turnips and many crops in the garden (destroying often whole fields while in their seedling leaves) is an animal that wants to be better known. The country people here call it the turnip-fly and black dolphin; but I know it to be one of the Coleoptera; the "Chrysomela oleracea, saltatoria, femoribus posticis crassissimis." In very hot summers they abound to an amazing degree, and as you walk in a field or in a garden, make a pattering like rain, by jumping on the leaves of the turnips or cabbages3.

by taking their tail in their mouth and letting it go suddenly. When it prepares to leap, our larva first erects itself upon its anus, and then bending itself into a circle by bringing its head to its tail, it pushes forth its unguiform mandibles, and fixes them in two cavities in its anal tubercles. All being thus prepared, it next contracts its body into an oblong, so that the two halves are parallel to each other. This done, it lets go its hold with so violent a jerk that the sound produced by its mandibles may be readily heard, and the leap takes place. Swammerdam saw one, whose length did not exceed the fourth part of an inch, jump in this manner out of a box six inches deep; which is as if a man six feet high should raise himself in the air by jumping one hundred and fortyfour feet! He had seen others leap a great deal higher."-E. T. B.

3 In this work of destruction, although a share is taken by the Haltica oleracea, GEOFFR. (Chrysomela oleracea, LINN.) the most powerful agent is the Halt. nemorum, a still smaller beetle, about the twelfth part of an inch in length, black above, and having a yellowish stripe along the middle of each of its wing-cases. The injury inflicted on the turnip crops by these pigmy depredators is in some years immense: it has been calculated that in Devonshire alone, in 1786, the damage inflicted by them on the agriculturist amounted to not less than one hundred thousand pounds. The turnip-fly, or turnip-flea (as Messrs. Kirby and Spence propose to call it, not from its entomological affinities, but from its diminutive size and leaping powers) is the earliest enemy of the turnip crops. The instant that the plant appears above the ground, it is attacked by the little insect which destroys the seedling or smooth leaves, and the plant perishes in consequence. After the rough leaf has made its appearance, the crop may generally be regarded as safe from severe injury from this cause. This is the more fortunate, as the turnip-fly is always active during the summer, and is ever at hand prepared by regaling itself on its favourite food to ruin the hopes of the farmer. Rapid growth of the crop (and to secure rapid growth good cultivation and suitable manure are the effectual means,) is the most natural way of preserving it: while it is in the smooth leaf it is in jeopardy; when in the rough leaf its danger from this enemy may be looked upon as escaped.

But although the turnip may have assumed the rough leaf, and have

There is an Estrus, known in these parts to every ploughboy; which, because it is omitted by Linnæus,

thus attained a stage of its existence when the attacks of the black fly are no longer to be dreaded, it is not even then to be regarded as absolutely safe. In some seasons, particularly in those when the summer is marked by a long continuance of drought, another pest is inflicted on the crop, which is to the full as destructive as the ordinary fly. In the summer of 1835, this enemy was active at Selborne, and many of the fields on the malm lands were laid waste by its ravages: the only good turnips to be seen in the district, in the autumn of that year, were in the neighbourhood of Oakwoods, on the sandy lands near the Forest. Here, as elsewhere, the crops on the chalky soils appear to have been most obnoxious to injury; although the damage was by no means limited to them.

Mr. Yarrell has given to the Zoological Society some account of the visitation of the black worm, as it was generally called, in 1835. Early in July, he says, the "yellow fly" was seen upon the young turnips. It was remembered by some that this was the fly which prevailed in 1818, and which was followed by the caterpillars known by the name of the "blacks." The appearance of the perfect insect was quickly succeeded by that of the black caterpillar, or turnip pest, feeding in myriads on the leaves of the turnips, but leaving their fibres untouched. So complete and so rapid was the destruction in some instances, that a whole field has been found, in two or three days, to present only an assemblage of skeletonized leaves; and this too when the plants had attained a considerable size. The destruction of the leaves caused, in most cases, the loss of the root also: and where the root did not altogether perish, it became pithy, and of little comparative value. A second and even a third sowing were necessary, in consequence of the destruction of the earlier crops; and, so extensive was the failure, that large importations from the continent were required to supply the deficiency. The caterpillar, finally casting its black skin and assuming a slaty appearance, buried itself in the ground, forming a cocoon from which the perfect fly quickly emerged, filled with eggs and prepared to renew the swarms of fresh depredators. By these repeated broods the devastation was successively continued, till it was at length put an end to on the occurrence of those heavy rains in September by which the unusually dry and lengthened summer was terminated.

The insect produced from the black caterpillar is a kind of saw-fly, or Tenthredo, little more than a quarter of an inch in length, of a pale yellow colour, with a black head and a black patch on each side of the thorax: it is believed to be the Athalia Centifolia, LEACH; but the species of this genus resemble each other so nearly as to render the discrimination of them difficult.

A visitation of these pests in Norfolk, in 1782, was described by Mr. Marshall in the following year, in a paper contributed by him to the Philosophical Transactions. They are there spoken of under the name of the black canker caterpillar. Many thousands of acres, on which a

is also passed over by late writers; and that is the Curvicauda of old Mouffet, mentioned by Derham in his Physico-Theology, p. 250: an insect worthy of remark for depositing its eggs as it flies in so dexterous a manner on the single hairs of the legs and flanks of grass horses. But then Derham is mistaken when he

fairer prospect for a crop of turnips had not been seen for many years, were ploughed up in consequence of their attacks. Their ravages were preceded by the appearance of the yellow fly in immense numbers; and it was believed, as they occurred most freely on the coast, that they arrived from across the ocean: some fishermen even declared that they saw them come in cloud-like flights. But there is no sufficient reason for attributing to them other than a home origin. They are seen here every summer; although it is only occasionally, when circumstances combine to favour an extraordinarily rapid growth and frequent broods among them, that they are so numerous as to become extensively destructive.

Against the attacks of the black caterpillar no preventive has yet been suggested. When it prevails the most effectual means of keeping it under is by freely sprinkling the infested fields with lime, and renewing the sprinkling as often as the fine powder may happen to be carried away by the wind. The same process appears also to have been the most successful that has yet been resorted to against the attacks of the little enemy of every season. It is strongly recommended in a report on the ordinary turnip-fly, published in 1834 by the Doncaster Agricultural Society, as the result of a very extensive correspondence, instituted with the especial view of collecting, from all parts of England, information on a subject of so much importance to the agriculturist.—E. T. B.

It is by no means surprising that Gilbert White should have believed that the horse bot-fly had been omitted from his works by Linnæus; for it could scarcely have occurred to him to look for it, either in the Systema Naturæ or in the Fauna Suecica, under the very inappropriate name of Estrus Boris: yet by that name he would have found it described in both those works. The habitats assigned to it by Linnæus, the stomach of the horse and the back of kine, show that he confounded together two distinct insects, the maggots of which infest the several situations referred to by him. The maggots of the one, known by the names of wormals or warbles and sometimes by that of bots, are found beneath the skin of cattle: these are the larvae of the true Estrus Bovis, the perfect fly of which was probably unknown to the great Swedish naturalist. The maggots of the other, known, in common with those of some other species, by the name of bots, are found with the larvæ of those other bot-flies in the stomachs of horses. The one whose habits are described by White, may be called the spotted-winged bot-fly: it is described by Linnæus under the erroneous name of Estrus Boris; by Mr. Bracy Clark under the name of Estrus Equi; and is, in modern

advances that this Estrus is the parent of that wonderful star-tailed maggot which he mentions afterwards;

systems, the Gasterophilus Equi, LEACH; the generic appellation being founded on the aptitude of the maggots for residence in the stomachs of living animals.

Mr. Bracy Clark, who has well described the habits of these insects in his Observations on the Genus Estrus, published in the third volume of the Linnean Transactions, and subsequently in an Essay on the Bots of Horses, dwells with more detail on the fact recorded in the text. Speaking of the spotted-winged bot-fly, he says, "The mode pursued by the parent fly to obtain for its young a situation in the stomach of the horse is truly singular, and is effected in the following manner::-When the female has been impregnated, and the eggs are sufficiently matured, she seeks among the horses a subject for her purpose, and approaching it on the wing, she holds her body nearly upright in the air, and her tail, which is lengthened for the purpose, curved inwards and upwards: in this way she approaches the part where she designs to deposit the egg; and suspending herself for a few seconds before it, suddenly darts upon it, and leaves the egg adhering to the hair: she hardly appears to settle, but merely touches the hair with the egg held out on the projected point of the abdomen. The egg is made to adhere by means of a glutinous liquor secreted with it. She then leaves the horse at a small distance, and prepares a second egg, and, poising herself before the part, deposits it in the same way. The liquor dries, and the egg becomes firmly glued to the hair: this is repeated by various flies, till four or five hundred eggs are sometimes placed on one horse.

"The inside of the knee is the part on which these flies are most fond of depositing their eggs, and next to this on the side and back part of the shoulder, and less frequently on the extreme ends of the hairs of the mane. But it is a fact worthy of attention, that the fly does not place them promiscuously about the body, but constantly on those parts which are most liable to be licked with the tongue; and the ora therefore are always scrupulously placed within its reach. Whether this be an act of reason or of instinct, it is certainly a very remarkable one. I should suspect, with Dr. Darwin, it cannot be the latter, as that ought to direct the performance of any act in one way only."

The eggs thus deposited are not, in Mr. Bracy Clark's opinion, removed from the hairs by the moisture of the horse's tongue, aided by its roughness, in the act of licking, and thus conveyed to the stomach: but remain, he conceives, attached to the hairs for four or five days until they have become “ripe, after which time the slightest application of warmth and moisture is sufficient to bring forth in an instant the latent larva. At this time, if the tongue of the horse touches the egg, its operculum is thrown open, and a small active worm is produced, which readily adheres to the moist surface of the tongue, and is from thence conveyed into the stomach." For the manner in which the larva affixes itself in the stomach by means of the two hooks with which it is furnished at its smaller extremity; its mode of growth; its detachment, when fully

for more modern entomologists have discovered that singular production to be derived from the egg of the Musca Chameleons: see Geoffroy, t. 17. f. 4.

A full history of noxious insects hurtful in the field, garden, and house, suggesting all the known and likely means of destroying them, would be allowed by the

grown, from the stomach; its passage through the intestines to remain, during its pupa state, in some convenient spot of dung or earth; some anatomical particulars respecting it; and many other facts relating to the fly in its various stages, as well as to other species; the reader is referred to the paper in the Linnean Transactions, from which the above extracts are taken. Interesting as they are, the explanation of them would extend this note to too great a length, and would carry it altogether away from the point to which it is chiefly directed, the admirable provision adverted to in the text for securing for the bots the only habitation in which they could exist.

One other observation may, however, be permitted. Mr. Bracy Clark does not appear to regard these larvæ of the bot-fly as being productive of injurious effects to horses; but, on the contrary, he suggests that the local irritation produced by them may be useful in preventing the access of disease. The opinion expressed by him on this point in 1796 would seem to have been confirmed by his subsequent experience; for, nearly twenty years afterwards, in 1815, he gave the name of salutiferus to a species then discovered by him in a somewhat curious manner. Having observed in the stomachs of dead horses which he had examined several larvæ which appeared to him to be different from any that he had previously seen, he removed some of them and forced them down the throat of his own horse: two or three months afterwards the pupa were received from the latter, and were placed on some light mould in a jar, in which they quickly buried themselves. This curious attempt at breeding a bot-fly, the first experiment of the kind on record, proved thoroughly successful; and Mr. Bracy Clark was rewarded for his sagacious discrimination, by obtaining, on the developement of the fly, specimens of a nondescript species of a genus which he had made especially his own.-E. T. B.

The singular and highly interesting larva of the Stratiomys Chamaleon, DE GEER, has been repeatedly figured and described, and the use of the star-like circle of feathered hairs appended to its tail, as a means of suspending that part and the orifice of the respiratory tube in their centre, has been often explained: it is among the most beautiful as well as the most curious contrivances resorted to for such a purpose by ever varying nature. The eggs from which these larvæ are produced are affixed by the parent fly to plants living in the water in which the developement of the maggot is to take place: those seen by Messrs. Kirby and Spence were "arranged like tiles on a roof one laid partly over another, on the under side of the leaves of the water-plantain.”— E. T. B.