the blue-bottle fly must be known to many; the silk-worm's eggs again are not unknown; but the generality of insects' eggs are so concealed, and so little conspicuous, that they are found with difficulty. Examples of larvæ are numerous; the maggots found in wasps' nests and used in fishing, -the maggots in apples and nuts, the maggots in cheese, and in decaying substances, and the caterpillars which devour our cabbages, and those which spin webs on our apple, pear, and plum trees, are familiar to us all: these

are insects in the larva state. The pupa state is more difficult to find, because insects generally crawl away into crevices or hide themselves underground, before changing to this state; an angular pupa, of a green colour, with small black spots, which produces a common white butterfly, may, however, be frequently seen on palings and garden walls, and the smooth brown pupa of moths are continually dug up in gardens. The imago, or perfect state, is exemplified in butterflies, moths, gnats, flies, wasps, bees, ants, beetles, grasshoppers, earwigs, cockroaches, bugs, fleas, may-flies, and dragon-flies. All descriptions of insects in scientific works relate to the imago state, unless the contrary is distinctly expressed.

The mode in which the life of an insect is passed, differs very widely in the various states of its existence it often happens that the larva inhabits the water and the imago the air; sometimes the larva inhabits the water, the pupa inhabits the earth, and the imago returns to the water. The following brief histories will in some degree exemplify this.

History of the Simulia.*- The eggs of the Simulia or sandfly (sometimes also called the mosquito), appear to be at present unknown; there is, however, little doubt, that like those of other gnats, they are deposited on the surface

* Authority;-M. Fries, in 'Entomologisches Archives.'

The

of the water, and in that situation are hatched by the warmth of the sun combined with the moisture of the water. larva is found on the stems of water-plants (Phellandrium, &c.), on those portions which are always covered by the water: it is long, cylindrical, considerably thickened posteriorly, and nearly transparent; its head is distinctly separated from the body, and is of an oblong form; it has four jaws moving horizontally, each bifid at the tip, and two little horns in the usual place of antennæ, inserted in the front of the head, rather towards each side; each of these is composed of two joints, the first or basal joint stout, the second or apical one, divided into many rays, which fold back on the first joint: there are two very small eyes on each side of the head. The body of the larva is divided into twelve segments, besides the head; of these, the second is incrassated, and furnished below with a retractile conical foot; the last segment is very minute, and furnished with two small prehensile feet: the air-tubes, so very plainly seen in other aquatic larvæ, are totally wanting; neither is there the least appearance of spiracles or breathing-holes in the sides.

The motion of the larva in the water is tolerably brisk; but on any object coming in contact with it, it instantly becomes motionless, attaches itself by the anterior prehensile foot, and remains for a long time perfectly still and immovable. When it moves from one place to another, its progression is undulating, somewhat like that of a leech, being performed in this manner: -the anterior foot is firmly attached to some object, then the posterior pair of feet are brought up to it, the back arching up during the operation; the anterior foot then releases its hold; the body is again elongated, the foot attached further on, and the posterior feet again brought up to it. The food of the larva is unknown: when full grown, it spins a little silken sheath, in

shape like a watch-pocket, which is attached to the plant

frequented by the larva, and in this it shortly changes to a pupa in an upright position: the case being always open at top, the head and shoulders of the pupa are seen projecting above it. The pupa much resembles that of a moth: it is perfectly motionless, of a brown colour, and exhibits very distinctly the parts of the perfect insect through its skin: from the back of its head arise, on each side, four hair-like appendages; these are tubular, and appear to be designed for breathing. About the sixth of July the little creature bursts from its sheath; the case of the chrysalis opens in a right line down the back, and the perfect insect emerges through the opening, surrounded by a bubble of air, and slowly begins to unfold its wings under the water; finally, its skin being cast, and maturity attained, the imago disengages itself from its former habitation, and mounts within its bubble to the surface of the water, when the bubble bursts, and the creature, with its new organs, has acquired a new element. The imago is a small black fly, with two large transparent wings, which, when at rest, repose horizontally on its back; moderately long legs, and short stout anten

næ: it flies with ease, and somewhat sportively, rising and falling. In this country it is found in the damp parts of woods, and other similar situations; but, happily, in very limited numbers.

There is scarcely any creature more annoying to men and animals, than this little fly: its attacks are made in innumerable multitudes, and it is troublesome, not only from the pain and inflammation caused by its bite, but also from the intolerable itching occasioned by its crawling over the skin. In the woody and marshy parts of Lapland, these flies swarm in the months of July and August; nay, even the summits of the highest mountains, though capped with perpetual snow, impose no obstacle to their progress.

Among the numerous gnats and flies which feed on blood, these are the most to be feared; impelled by an insatiable thirst they make their attack, and will have blood; nothing can repel or deter them. Whenever the garment of a traveller has accidentally slipped aside, and discovered a portion of his skin, however small, that exposed portion is instantly streaming with blood: in the southern parts of Lapland they are less troublesome than in the northern, although clouds of them occasionally appear, performing their evolutions in the air.

The Simulia seems to have adopted the world for its country: no known land appears to be without it; all temperatures suit it-the polar snows and the blaze of tropical sands. Yet all the flies of which travellers complain as so dreadfully annoying, are not Simulia;-many of our commonest gnats have a similar taste for blood. Although from what is related, there can be no doubt that the blood of man is an acceptable food to the Simulia, yet it is remarkable that the greatest multitudes of these creatures inhabit those bleak, inhospitable, and almost inaccessible regions where the foot of man seldom treads, and where other warm-blooded animals are scarcely known to exist. It is clearly ascertained that the female Simuliæ alone suck the blood of man; the males spend their lives among the leaves of trees, or settle on flowers, from which they appear to derive nutriment; it is therefore far from impossible that, on the failure of animal, the females also may have recourse to vegetable food.

History of the Ichneumon.-There are many butterflies and moths which increase so rapidly, that, without a check, their caterpillars would, in two or three years at the utmost, devour every green leaf on the face of the earth, and render it incapable of supporting its present inhabitants. The ichneumons are evidently created to act as a check to this

devastation: they are generally small insects, with slender bodies, and have four transparent wings: they are very active, running about the stems and leaves of plants in search of caterpillars, and fly very readily. The ichneumons are of many kinds: more than a thousand species have been described by naturalists; and it is probable that every butterfly, and every moth, indeed, almost every insect, has one peculiar to itself: the history of them all is nearly similar.

The caterpillar of the tiger-moth is one of the most destructive; it devours, indiscriminately, lettuces, radishes, beans, peas and every other early production of our gardens, and is most abundant in the spring, when these plants are being reared: it is a very rough, hairy caterpillar, black above, with a red fringe on each side, and is preyed on by several ichneumons. The largest ichneumon (Pimpla Instigator) of the tiger-moth (Arctia caia) is often about an inch long, but varies much in size; it has a black body and red legs, and emits a remarkably strong smell, something like burning pitch. In the spring, this ichneumon may be seen coursing over the leaves of lettuces, nettles and currantbushes, on strawberry-beds, &c., hunting for the object of its attack. When it has found a caterpillar, it seizes it behind the head with its jaws; at this operation the caterpillar loosens its hold of the plant on which it was feeding, rolls itself suddenly into a ring, erects its bristles as stiffly as possible, and falls to the ground: if the fall is great and among twigs, the ichneumon is sometimes dislodged, but this rarely happens.

The female ichneumon has three bristles at its tail; the middle one of these appears to be a tube for conveying its eggs into the body of the caterpillar, and is called an ovipositor, the outer ones seem to serve as protectors to this ovipositor, and not to be used for piercing the caterpillar. When the caterpillar can fall no farther, is frequently un