the rain-bow, and have a smoky tinge, forming a cloud or broad band across the middle of the first pair; the veins are brownish. The body of the female measures rather more than one fifth of an inch in length; that of the male is smaller. In the year 1828, I observed these saw-flies, on cherry and, plum trees, in Milton, on the tenth of May; but they usually appear towards the end of May or early in June. Soon afterwards some of them begin to lay their eggs, and all of them finish this business and disappear within the space of three weeks. Their eggs are placed, singly, within little semicircular incisions through the skin of the leaf, and generally on the lower side of it. The flies have not the timidity of many other insects, and are not easily disturbed while laying their eggs. On the fourteenth day afterwards, the eggs begin to hatch, and the young slug-worms continue to come forth from the fifth of June to the twentieth of July, according as the flies have appeared early or late in the spring. At first the slugs are white; but a slimy matter soon oozes out of their skin and covers their backs with an olive-colored sticky coat. They have twenty very short legs, or a pair under each segment of the body except the fourth and the last. The largest slugs are about nine twentieths of an inch in length, when fully grown. The head, of a dark chestnut color, is small, and is entirely concealed under the forepart of the body. They are largest before, and taper behind, and in form somewhat resemble minute tadpoles. They have the faculty of swelling out the forepart of the body, and generally rest with the tail a little turned up. These disgusting slugs live mostly on the upper side of the leaves of the pear and cherry trees, and eat away the substance thereof, leaving only the veins and the skin beneath untouched. Sometimes twenty or thirty of them may be seen on a single leaf; and, in the year 1797, they were so abundant, in some parts of Massachusetts, that small trees were covered with them, and the foliage entirely destroyed; and even the air, by passing through the trees, became charged with a very disagreeable and sickening odor, given out by these slimy creatures. The trees attacked by them are forced to throw out new leaves, during the heat of the summer, at the ends of the twigs and branches that still remain alive; and this unseasonable foliage, which should not have appeared till the

In a

next spring, exhausts the vigor of the trees, and cuts off the prospect of fruit. The slug-worms come to their growth in twenty-six days, during which period they cast their skins five times. Frequently, as soon as the skin is shed, they are seen feeding upon it; but they never touch the last coat, which remains stretched out upon the leaf. After this is cast off, they no longer retain their slimy appearance and olive color, but have a clean yellow skin, entirely free from viscidity. They change also in form, and become proportionally longer; and their head and the marks between the rings are plainly to be seen. few hours after this change, they leave the trees, and, having crept or fallen to the ground, they burrow to the depth of from one inch to three or four inches, according to the nature of the soil. By moving their body, the earth around them becomes pressed equally on all sides, and an oblong oval cavity is thus formed, and is afterwards lined with a sticky and glossy substance, to which the grains of earth closely adhere. Within these little earthen cells or cocoons the change to chrysalids takes place; and, in sixteen days after the descent of the slug-worms, they finish their transformations, break open their cells, and crawl to the surface of the ground, where they appear in the fly form. These flies usually come forth between the middle of July and the first of August, and lay their eggs for a second brood of slugworms. The latter come to their growth, and go into the ground, in September and October, and remain there till the following spring, when they are changed to flies, and leave their winterquarters. It seems that all of them, however, do not finish their transformations at this time; some are found to remain unchanged in the ground till the following year; so that, if all the slugs of the last hatch in any one year should happen to be destroyed, enough, from a former brood, would still remain in the earth to continue the species.

The disgusting appearance and smell of these slug-worms do not protect them from the attacks of various enemies. Mice and other burrowing animals destroy many of them in their cocoons, and it is probable that birds also prey upon them when on the trees, both in the slug and the winged states. Professor Peck has described a minute ichneumon-fly, stated by Mr. Westwood

to be a species of Encyrtus, that stings the eggs of the slug-fly, and deposits in each one a single egg of her own. From this, in due time, a little maggot is hatched, which lives in the shell of the slug-fly's egg, devours the contents, and afterwards is changed to a chrysalis, and then to a fly like its parent. Professor Peck found that great numbers of the eggs of the slug-fly, especially of the second hatch, were rendered abortive by this atom of existence.

Ashes or quicklime, sifted on the trees by means of a sieve fastened to the end of a pole, was recommended, by the late Hon. John Lowell, of Roxbury, for the destruction of the slugs; and it is found to answer the purpose. It is probable that Mr. Haggerston's almost universal remedy may prove to be still more effectual.

The saw-flies, though undoubtedly belonging to the order Hymenoptera, depart from the general characters thereof more than any other insects in it. They are more dull and heavy in all their motions; they have not the powerful jaws of the predaceous tribes, nor the long and slender lower jaws and tongue of those that subsist upon honey. They live but a short time, and their food appears to be pollen, the tender parts of leaves, and sometimes the plant-lice and other soft-bodied insects frequenting flowers. In the stiffness of their upper wings, and the heaviness of their flight, they somewhat resemble beetles, and, analogically, may be said to typify the Coleoptera, or, in other words, they may be called the beetles of the Hymenoptera. They will be found, on comparison, to have some features in common with the crickets, which, with the earwigs, are also the representatives of the Coleoptera. Although they differ essentially from butterflies and moths, the resemblance of most of their young to caterpillars, in form and in habits, is very striking and remarkable. Hence the saw-flies plainly show the relation existing between the orders Lepidoptera and Hymenoptera, and serve closely to connect them together.

The next piercing insects to be described belong to the family of UROCERIDE, or horn-tails, so called because they have a horny point at the end of the body. The Germans call them wood-wasps. Their antennæ are slender, and thread-like, or tapering. They have a large head, convex before, and flat behind

where it joins the thorax. Their wings are long, narrow, and strong, and overlap on the top of the back, when closed. The body is very long, and nearly or quite cylindrical; the thorax and the after part of the body are of equal thickness, and are closely joined together. The horn, at the end, is short, and conical or triangular, in the males; longer, and sometimes spear-pointed, in the females. Moreover the latter are provided with a long, cylindrical borer, hinged to the middle of the belly, which is furrowed to receive it. The borer usually extends some distance beyond the end of the body, and consists of five pieces. The two outermost are grooved within, and, when shut, form a hollow tube or scabbard to the others, one of which represents the two backs of the saws of the saw-flies, joined together, and encloses two needles for boring holes. The part, serving for a back to these needles, is notched on each side, and the needles themselves, which are as fine as a hair, and as strong and elastic as wire, have several small teeth along the lower side towards the end. These needles, and the back in which they play, are so connected as to appear to be only a single spear-pointed awl. With this complicated and powerful tool the females bore holes into the trunks of trees, wherein they drop their eggs. Their young are cylindrical and fleshy grubs, of a whitish color, with a small, rounded, horny head, and a pointed and horny tail. They have six very small legs under the forepart of the body, and are provided with strong and powerful jaws, wherewith they bore long holes in the trunks of the trees that they inhabit. Like other borers, these grubs are wood-eaters, and often do great damage to pines and firs, wherein they are most commonly found. When fully grown, the grubs make thin cocoons of silk, interwoven with little chips, in their burrows, and in them go through their transformations. The chrysalis is somewhat like the winged insect in form, but is of a yellowish white color, till near the time of its last change, and the wings and legs are folded under the breast; in all these respects it agrees with the chrysalids of other Hymenopterous insects. After the chrysalis skin is cast off, the winged insect breaks through its cocoon, creeps to the mouth of its burrow, and gnaws through the covering of bark over it, so as to come out of the tree into the open air. It is stated that the

grubs of the large species come to their growth in seven weeks after the eggs are laid. If this be true, and it seems hardly possible, the chrysalis state must last a long time, for the perfected insects have been known to come out of timber that had been cut up and applied to mechanical uses by the carpenter. Some persons have supposed that they attacked only diseased and decayed trees, in which it must be admitted they are often found in great numbers. But many instances might be mentioned of their appetite for sound wood also, and it is probable that the presence of these insects, like that of many others, is the cause and not the consequence of the decay of the trees wherein they live. It is stated in the London "Zoological Journal," that two hundred Scotch firs have been destroyed by the Urocerus Juvencus, in the woods of Henham Hall, the seat of the Earl of Stanhope, their trunks being bored through and through by the grubs of this inMr. Westwood relates that a piece of wood, twenty feet in length, from a fir-tree in Bewdley Forest, Worcestershire, England, was found to be so intersected by the burrows of these grubs, as to be fit for nothing but fire-wood; and that the winged insects continued to come out of it, at the rate of five, six, or more each day, for the space of several weeks. states, on the authority of Sir Joseph Banks, that

sect.

*

Mr. Marsham

several specimens of Urocerus gigas were seen to come out of the floor of a nursery in a gentleman's house, to the no small alarm and discomfiture of both nurse and children. The grubs must therefore have existed in the boards or timbers before they were employed in building, and these materials would not have been used if in a decayed state. The sexes of most of these insects differ considerably in size and color, and in the shape of their body and of their hind-legs. There are not many different kinds, but they are very prolific, and abound in mountainous districts, and in temperate climates, where forests of pines and firs prevail. A new order was proposed for their reception by Mr. Macleay, and was named Bomboptera, on account of the humming sound that they make in flying. Their young partake of the nature of the wood-eating grubs of the capricorn beetles, which therefore they

"Introduction to the Modern Classification of Insects," Vol. II., p. 118.