[In the latter part of the month of August we were traveling through Jefferson county, N. T., and observed through the whole country that the Basswood trees, which are very abundant in that part of the country, looked as brown and dry as though some terrible blight had struck them all dead. On examination We found this appearance was owing to the leaves being all devoured, leaving but the skeleton of fibres; not a leaf had escaped throughout the immense forests which we passed on a journey of some thirty miles or more. The insects had mostly disappeared, but after a long and eager search we found one tree, the leaves of which, though reduced to skeletons, were yet thickly covered with the insects. We immediately sent specimens to Prof. Harris, requesting such information as he possessed respecting them, and he has very kindly complied. Insects that appear in such swarms, and commit such havoc, should be known. The other insect, the "Drop-worm," described by Prof. Harris below, was sent us from Tennessee by Mr. Robert Meston, whose note we publish among correspondence. - Ed].

Among the leaf-beetles that are injurious to vegetation are those belonging to the tribe called Hispadae. Such are the little insects which you lately sent to me, and which you found to have destroyed the foliage of the Basswood, or American Linden (Tilia Americana), in Jefferson county, N. Y. A variety of the same insect attacks the leaves of the White Oak, and occasionally those of the Apple tree, also. These leaf-beetles are described in the second edition of my Treatise, pp. 105 to 107; and a more full account of them, with figures of the grub and chrysalis, will be found in the first volume of the Boston Journal of Natural History, pp. 141 to 151.

The day before your letter came to hand, I found one of these beetles, which had just emerged from a leaf of the Linden, and I saw several other leaves on the same tree that had been eaten by insects of this kind. In the summer of 1851 the White Oaks in some parte of Long Island suffered very much from their attacks; and, with this communication, you will receive one of the leaves, showing in what way and to what extent they were affected.*

Your insect is the Rosy Hispa, or Hispa rosea?, of Weber, otherwise called Hispa quadrata by Fabricuis, and Hispa marginata by Say. The accompanying rude and very magnified sketch will give an idea of the form of this pretty leaf-beetle, and the line at the side of it indicates its natural size, which rarely exceeds one-fifth of an inch in length. Its body is light red above, ornamented with short blood-red lines, and is mostly blackish beneath. The antennas are black, and the legs are reddish-yellow. The thorax is rough with small indentations, or punctures, as they are called; the wing-covers are notched around the outer edges, have raised ribs upon them, and deep punctures in the intervals. The Rosy Hispa may be found abundantly in May and June on the leaves of the Shad-bush, or Amelanchier Canadensis and on other shrubs of the same family, the leaves of which it devours. The variety which inhabits the Oak differs in being of a reddish-yellow color, ornamented with blackish-red lines. This difference may be occasioned by its food, or by other causes of an accidental nature.

The female Hispa deposits her eggs, for the most part, singly, on the upper surface of the leaves. These eggs are glued fast to the leaves, and are covered with a rough, blackish crust. The grubs, hatched from the eggs, immediately penetrate into the pulpy substance of the leaf, which they devour, leaving the cuticle, or skin of the leaf, both above and beneath, untouched. The part of the leaf thus, as it were, undermined, becomes dry and brown, and through the semi-transparent cuticle, when held between the eye and the light, the grub may be seen in its burrow. The grub comes to its growth toward the end of July, and then measures from one-fifth to one-quarter of an inch in length. It is somewhat flattened, and tapers toward the hinder extremity. Its color is yellowish-white, except the head, the first segment, and the tail, which are blackish. It has six legs, a pair beneath the first, second, and third segments; and on each of the remaining segments, both above and beneath, except the last, there is a transverse horny spot, which is rough, like a rasp. The sides of these segments, also, are prominent, and are surmounted each with a little brownish tubercle, or wart. Early in August the grub is transformed to a chrysalis within its retreat.

The chrysalis, which is whitish at first, finally becomes brown. Like the grub, the sides of its body are prominent, and there are transverse rasps on the back and belly. In about one week afterward the insect casts off its pupa skin, and comes out a fully formed beetle, which has only to force a passage through the thin cuticle of the leaf in order to escape into the open air. The insect, probably, passes the winter in the beetle form in some place of concealment. Such is briefly a history of the transformations of this little Hispa.

The caterpillars, which, together with their cocoons, you sent to me, with the information that they were very destructive to the Arbor Vitae, Cedar, and other resinous plants in Tennessee, are the drop-worms, or basket-worms, referred to on page 819 of my Treatise, To their destructive powers I can testify from my own sorrowful experience; a fine Arbor Vitro tree, on which I had placed, in May, 1850, some of the cocoons received daring the previous autumn from Philadelphia, not having yet recovered from the effects of the ravages of the insects, though the latter were limited to one summer. These drop-worms are exceedingly curious and interesting in all their habits and transformations, the history of which might form the subject of a long memoir. But neither time not space will permit me to offer any more than a very short sketch of their history, which is drawn up from notes written in the years 1849 and 1850, when I had a colony of the living insects in keeping.

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* Quite similar to the manner in which the Basswood leaves are eaten. - Ed.

These insects inhabit the Swamp Cedar (Cupressus Thyoides), Arbor Vitro (Thuya oocidentalis), Larch (Larix Americana), and Hemlock (Abies Canadensis), with other resinous trees; but occasionally they attack the Linden, the Maple, and even fruit trees. They are common in the Middle and Southern States, and probably most of the Western States also; but hitherto they have not been discovered in New England. They belong to Mr. Guilding's American genus Oiketicus; and, as they do not seem to have received a scientific name, I shall venture to give them that of Oiketicus con-iferarum, from their preference to trees of the cone-bearing tribe. The species is probably the same as the one noticed by my lamented friend, the late Mr. Edward Doubleday in Neuman's Entomologist, No. 7, pp 97-98; but the male insect does not agree with the figure, copied from one of Abbot's drawings in the same work, nor does it correspond any better to Guilding's figure of Oiketicus McCayi, though about the same size.

As soon as the drop-worms are hatched, they make and conceal themselves in little silken cases, open at each end, and covered externally with bits of leaves, twigs, etc. These cases are enlarged, as the insect increases in size, by the addition of more materials within and without, and -finally become oblong oval pods, with long somewhat cylindrical extremities. The inhabitant carries its house about on its back, as a snail does its shell, when it is moving and feeding; fastens it by a few threads when it wishes to rest; or lets it drop by a thread when it wishes to descend from one branch to another: hence, in Philadelphia, where these insects are abundant, they have acquired the name of drop-worms. These worms attain their full size by the middle of September, and then fasten the upper end of their cases to a twig of the tree by a strong silken band. The weight of the case, with its elasticity, closes the upper orifice, from which the worm has been accustomed to protrude its head and fore legs when feeding; the insect then turns round within its pod, so as to direct its head toward the lower cylindrical orifice, and thus awaits its change to a chrysalis.

The worms which produce the female insects are much larger than those of the males, and there is the same difference in the size of their pods and of their chrysalids. Female worms attain the length of one inch and a half, those of the males only about one inch. The head and fore part of the body are white, spotted with black; the rest of the body is livid or blackish. The first three segments are each provided with a pair of &tout jointed claw-like legs. The tail and four intermediate segments are furnished with a pair of very short holders, or prop-legs. The male chrysalis is a little more than six-tenths of an inch long, of a dark brown color, and exhibits the sheaths of the wings, and limbs of the future moth, which escapes from it toward the end of September or early in October, immediately before which the chrysalis forces itself half way out of the lower end of its case. The female chrysalis is nine-tenths of an inch long, or more, of the same color as that of the males, but without any vestige of wing-sheaths or limbs. There is a prominent ridge over the fore part of the body.

When the included female is matured, the skin of the chrysalis splits at the ridge, so as to form an opening in the shape of the letter T, and through this opening the approaches of the male moth are made, the female remaining all the while not only enclosed in her pod, but also encased in the skin of the chrysalis. In this skin, also, she lays her numerous eggs, gradually withdrawing her emaciated body as she fills the pupa skin, and finally closing the upper part of the skin with a thick layer of fawn-colored down, stripped from her own body. Having finished her labors, she crawls out of the pod, entirely shriveled up, drops off and dies, or more rarely perishes at the mouth of her pod. She is found to be entirely destitute of wings, and her legs are extremely minute, and resemble little tubercles. The male moth, on the contrary, is fully provided with wings and limbs. Its body, which measures rather more than half an inch in length, is covered with long blackish-brown down. Its wings are semi-transparent, and are very scantily clothed with blackish scales, which are thickest on the margins and veins. The white spot, represented by Mr. Abbot on the fore wings of his figure, is entirely wanting in all the males that I have seen.

The antennae are curved at the tips, and are doubly feathered from the base to beyond the middle. The tongue is not visible. The wings expand one inch and one-tenth, or more. The male moths are very impatient of confinement, and keep in constant motion, which renders it very difficult to obtain perfect or unrubbed specimens. The eggs remain secure in the shell or skin of the female chrysalis, enclosed in the suspended pods, through the winter, and are hatched in the spring when the trees are well clothed with leaves, upon which the little worms, having left the pods, immediately disappear, and each one begins to cover its tender body with a silken and leafy case. The figures represent one of the pods or cocoons, suspended by a twig, when the insect has prepared for its final transformation; also a male moth, both of the natural size.

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