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their backs, like the Tineæ; certain kinds live within the stems of plants, and devour the pith; and wheat, in Europe, is said to suffer considerable injury from internal feeders (Cephus pygmæus) of this kind. When fully grown, most of them go into the ground, and enclose themselves in thin silken cocoons, of an oblong oval shape, coated with grains of earth. Some make much thicker cocoons, in texture resembling parchment, and fasten them to the plants on which they live, or conceal them in crevices, or under leaves and stones on the ground. They generally remain for a long time unchanged in their cocoons, most of them during the winter; are transformed to chrysalids, of a whitish color, in the spring, and come out in the winged form soon afterwards. Of some kinds there are two broods in the course of the summer, the false caterpillars of the first brood coming to their growth, and passing through all their transformations, within six or seven weeks from their first appearance.
The names of above sixty native species of saw-flies may be found in my “ Catalogue of the Insects of Massachusetts." Some of these are very interesting in their appearance and habits in the caterpillar state. In what follows an account will be given of one of the largest species, and of some smaller kinds, that have been found very injurious to cultivated plants.
Our largest saw-fly belongs to the genus Cimbex. This name was originally given by the Greeks to certain insects resembling bees and wasps, but not producing honey. It therefore applies very well to some kinds of saw-flies, such as the female of this species, which, at first sight, might be mistaken for a hornet. Her head and thorax are shining black. Her hind body is oval, and of a steel blue or deep violet color, with three or four oval yellowish spots on each side. Her antennæ are buff-colored, except at the base, where they are dusky; they are short, and end with an egg-shaped knob. Her wings are smoky brown, and semitransparent. Her legs are blue-black, and her feet pale yellow. The length of her body varies from three quarters to seven eighths of an inch, and her wings expand an inch and three quarters or more. In the manuscript lectures of the late Professor Peck, she is called Cimbex Ulmi, because she inhabits the elm. The male is the Cimbex Americana of Dr. Leach, and differs so much from the female, that it might be taken for a different species. His body is longer and narrower than that of the female, and wants the white spots on the sides; and there is a transverse, oval hole, filled with a whitish film, behind the thorax, which is hardly perceptible in the other sex. His hind legs are very thick; the shins are bowed, and hairy within; and the first joint of his feet ends with a stout hook, curved inwards. He often measures an inch in length, and his wings expand about two inches. These insects appear from the latter part of May to the middle of June, during which period the female lays her eggs upon the common American elm, the leaves whereof are the food of her young. The latter come to their growth in August, and then measure from one inch and a half to two inches in length. They are rather thick, and nearly cylindrical in form, and have twenty-two legs, or a pair to every ring except the fourth. They have a firm, rough skin, of a pale greenish yellow color, covered with numerous transverse wrinkles, with a black stripe, consisting of two narrow black lines, along the top of the back, from the head to the tail; and their spiracles, or breathing-holes, are also black. When at rest, they lie on their sides, curled up in a spiral form, and, in this position, look not much unlike some kinds of cockle or snail shells. Like all the false caterpillars of the genus Cimbex, this insect, when handled or disturbed, betrays its fears or its displeasure by spirting out a watery fluid from certain little pores situated on the sides of its body just above its spiracles. After its feeding state is over, it crawls down from the tree to the ground, and conceals itself under fallen leaves or other rubbish, and there makes an oblong oval, brown cocoon, very closely woven, as tough as parchment, and about an inch in length. In this the false caterpillar remains unchanged throughout the winter, and is not transformed to a chrysalis till the following spring. At length the insect bursts its chrysalis skin, and, by pushing against the end of its cocoon, forces off a little circular piece like a lid, and through the opening thus made it comes forth in its winged form.
For some years past many of the fir-trees, cultivated for ornament, in this vicinity, have been attacked by swarms of false caterpillars, and, in some instances that have fallen under my notice, have been nearly stripped of their leaves every summer, and in consequence thereof have been checked in their growth, and now seem to be in a sickly condition. These destructive insects agree in their habits and in their general appearance, in all their states, with the pine and fir saw-flies, described by Köllar,* by whose ravages whole forests of these trees have been destroyed in some parts of Germany. It is probable, however, that the American fir saw-flies are not identical with those of Europe, as they differ from them rather too much to have originated from the same stock; neither do they sufficiently agree with Dr. Leach's descriptions of Lophyrus Americanus, Abbotii, compar, &c.; and, therefore, I propose to name this apparently undescribed species Lophyrus Abietis, the Lophyrus of the fir-tree. The following is a description of the insect in its winged state. The two sexes differ very much from each other in size and color, and still more remarkably in the form of their antennæ. The male is the smallest, measures one quarter of an inch in length, and expands his wings about two fifths of an inch. His body is black above, and brown beneath; his wings are transparent, with changeable tints of rose-red, green, and yellow; and his legs are wholly of a dirty leather-yellow color. His antennæ resemble very short, black feathers, wide at the end, and narrowed to a point, and are curled inwards on each edge, so as to appear hollow. The genus Lophyrus derives its name from the plumelike crest on the heads of the male insects. The body of the female is about three tenths of an inch long, and her wings expand half an inch or more. She is of a yellowish brown color above, with a short blackish stripe on each side of the middle of the thorax; her body beneath and her legs are paler, of a dirty leather-yellow color; and her wings resemble those of the male. Her antennæ are short, taper to a point, consist of nineteen joints, and are toothed on one side like a saw. My specimens of this kind of saw-fly, which were raised from the caterpillars in the summer of 1838, came out of their cocoons towards the end of July in the same year; but I have also found them on pines and firs early in May. The European pine saw-flies lay their eggs in slits which they make with their saws in the edges of the leaves; and it is probable that our fir saw-flies proceed in the same way. In June and July the false caterpillars of the latter may be found on firs; and, according to notes made by me many years ago, the same insects, or some very much like them, were observed on the leaves of the pitch-pine also. They are social in their habits, living together in considerable swarms, and so thick that sometimes two may be seen feeding together on the same leaf, and sitting opposite to each other. In order to lay hold of the leaf more firmly they curl the hinder part of the body around it; and, if they are disturbed, they throw up their heads and tails with a jerking motion. When fully grown, they are from five to six tenths of an inch in length; they are nearly cylindrical in form, thickest before the middle, and tapering behind, and have twenty-two legs. The head, and the first three pairs of legs, are black. The body is of a pale and dirty green color above, with a light stripe along the top of the back, separating two of a darker green color; there are two dark green stripes on each side of the body; and the belly and proplegs are yellowish. When young, the two stripes on the back are much darker, and those on the sides are nearly black. The skin, though covered with very fine transverse wrinkles, is not rough, and, with a magnifying glass, a few short hairs may be seen scattered over it. After the last moulting their color fades, and they become almost yellow. The greater part of them then suddenly leave the trees, either by travelling down the trunks, or by falling from the branches to the ground. A few, either from weakness or from some other cause, remain on the trees, make their cocoons among the leaves, and rarely finish their transformations, most of them perishing from the internal attacks of ichneumon-grubs. Some creep into cracks in fences and into other crevices; but most of those which reach the ground bury themselves under decayed leaves, or among
* “Treatise," pp. 340 and 347.
roots of the grass, and, in such secure places, make their cocoons. The latter are oblong oval cases, of tough grayish silk, and measure nearly three tenths of an inch in length. In due time the insects change to saw-flies, and come out of their cocoons, one end whereof separates, like a lid, to allow of their escape. Although some of them are found to finish their transformations in August, it is probable that the greater part of them remain unchanged in the ground till the following spring
No means for the destruction of the caterpillars of the fir saw-fly have been tried here, except showering them with soapsuds, and with solutions of whale-oil soap, which has been found effectual. They may also be shaken off or beaten from the trees, early in the morning, when they are torpid and easily fall, and may be collected in sheets, and be burned or given to swine. For other means to check their depredations the reader may consult the articles on the pine and fir sawflies of Europe, contained in Köllar's “ Treatise.”
The following account of a kind of saw-fly which attacks the grape-vine is chiefly extracted from my “Discourse before the Massachusetts Horticultural Society, in 1832,” where the insect is named Selandria Vitis. The saw-fly of the vine is of a jet-black color, except the upper side of the thorax, which is red, and the fore legs and under side of the other legs, which are pale yellow or whitish. The wings are semitransparent, of a smoky color, with dark brown veins. The body of the female measures one quarter of an inch in length, that of the male is somewhat shorter. These flies rise from the ground in the spring, not all at one time, but at irregular intervals, and lay their eggs on the lower side of the terminal leaves of the vine. In the month of July the false caterpillars, hatched from these eggs, may be seen on the leaves, in little swarms, of various ages, some very small, and others fully grown. They feed in company, side by side, beneath the leaves, each swarm or fraternity consisting of a dozen or more individuals, and they preserve their ranks with a surprising degree of regularity. Beginning at the edge they eat the whole of the leaf to the stalk, and then go to another, which in like manner they