there are others that are concealed from observation in stems and roots, which they pierce in various directions, and devour only the wood and pith; their habits, in this respect, being exactly like those of the Ægerians among the Sphinges. These insects belong to a family of Bombyces, by some naturalists called ZEUZERADE, and by others HEPIALIDE, both names derived from insects included in the same group. The caterpillars of the Zeuzerians are white or reddish white, soft and naked, or slightly downy, with brown horny heads, a spot on the top of the forepart of the body which is also brown and hard, and sixteen legs. They make imperfect cocoons, sometimes of silk, and sometimes of morsels of wood or grains of earth fastened together by gummy silk. Their chrysalids, like those of the Ceratocampians, are provided with notched transverse ridges on the rings, by means of which they push themselves out of their holes when ready to be transformed. The moths differ a good deal from each other, although the appearance and habits of the caterpillars are so much alike. The antennæ in some are threadlike, or made up of nearly cylindrical joints put together like a string of beads; in others they are more tapering, and doubly pectinated or toothed on the under-side, at least in the males; and in Zeuzera, a kind of moth not hitherto found in this country, the antennæ resemble those of the Ceratocampians, being half-feathered in the males, and not feathered in the females. The wings are rather long and narrow, and are strengthened by very numerous veins. The female is provided with a kind of tube at the end of the body, that can be drawn in and out, by means of which she thrusts her eggs into the chinks of the bark or into the earth at the roots of plants.

Of the root-eaters there is one kind which is very injurious to the hop-vine in Europe. It is called Hepiolus Humuli, the hopvine Hepiolus. The caterpillar is yellowish white; the head, a spot on the top of the first and second rings, and the six fore-legs are shining brown, and it is nearly naked, or has only a few short hairs scattered over its body. It lives in the roots of the hop, and, when about to transform, buries itself in the ground, and makes a long, cylindrical cocoon or case, composed of grains of earth held together by a loose silken web. The chrysalis has transverse rows of little teeth on the backs of the abdominal rings,

and by means of them it finally works its way out of the cocoon and rises to the surface of the ea th; this being done, the included moth bursts its chrysalis shell, and comes forth into the open air. In moths of this kind (genus Hepiolus) the antennæ are very short, slender, almost threadlike, and not feathered or pectinated; the tongue is wanting or invisible; and the feelers are excessively small, and concealed in a tuft of hairs. The hop-vine Hepiolus has not yet been detected in Massachusetts; but we have a much larger species, known to me only in the moth state, which is the reason of my having given the foregoing account of the preparatory stages of a European species. This moth does not appear to have been described. It is named, in my Catalogue of the "Insects of Massachusetts," Hepiolus argenteomaculatus, the silver-spotted Hepiolus. Its body and wings are rather long. It is of an ashen gray color; the fore-wings are variegated with dusky clouds and bands, and have a small triangular spot and a round dot of a silvery white color near their base; the hind-wings are tinged with ochre-yellow towards the tip. It expands two inches and three quarters.

The locust-tree, Robinia pseudacacia, is preyed upon by three different kinds of wood-eaters or borers, whose unchecked ravages seem to threaten the entire destruction and extermination of this valuable tree within this part of the United States. One of these borers is a little reddish caterpillar, whose operations are confined to the small branches and to very young trees, in the pith of which it lives; and by its irritation it causes the twig to swell around the part attacked. These swellings, being spongy and also perforated by the caterpillar, are weaker than the rest of the stem, which therefore easily breaks off at these places. My attempts to complete the history of this insect have not been successful hitherto; and I can only conjecture that it belongs to the Ægerians, or possibly to the tribe of Bombyces.

The second kind of borer of the locust-tree is larger than the foregoing, is a grub, and not a caterpillar, which finally turns to the beetle named Clytus pictus, the painted Clytus, already described on a preceding page of this essay.

The third of the wood-eaters, to which the locust-tree is exposed, though less common than the others, and not so universally

destructive to the tree as the painted Clytus, is a very much larger borer, and is occasionally productive of great injury, especially to full-grown and old trees, for which it appears to have a preference. It is a true caterpillar, belonging to the tribe of moths under consideration, is reddish above, and white beneath, with the head and top of the first ring brown and shelly, and there are a few short hairs arising from minute warts thinly scattered over the surface of the body. When fully grown, it measures two inches and a half, or more, in length, and is nearly as thick as the end of the little finger. These caterpillars bore the tree in various directions, but for the most part obliquely upwards and downwards through the solid wood, enlarging the holes as they increase in size, and continuing them through the bark to the outside of the trunk. Before transforming, they line these passages with a web of silk, and, retiring to some distance from the orifice, they spin around their bodies a closer web, or cocoon, within which they assume the chrysalis form. The chrysalis measures one inch and a half or two inches in length, is of an amber color, changing to brown on the forepart of the body; and, on the upper side of each abdominal ring, are two transverse rows of tooth-like projections. By the help of these, the insect, when ready for its last transformation, works its way to the mouth of its burrow, where it remains while the chrysalis skin is rent, upon which it comes forth on the trunk of the tree a winged moth. In this its perfected state, it is of a gray color; the fore-wings are thickly covered with dusky netted lines and irregular spots, the hindwings are more uniformly dusky, and the shoulder-covers are edged with black on the inside. It expands about three inches. The male, which is much smaller, and has been mistaken for another species, is much darker than the female, from which it differs also in having a large ochre-yellow spot on the hind-wings, contiguous to their posterior margin. Professor Peck, who first made public the history of this insect*, named it Cossus Robinia, the Cossus of the Locust-tree, scientifically called Robinia. It is supposed by Professor Peck to remain three years in the cater

* See "Massachusetts Agricultural Repository and Journal," Vol. V., p. 67, with a plate.

man

pillar state. The moth comes forth about the middle of July. The same insect, or one not to be distinguished from it while a caterpillar, perforates the trunks of the red oak. Mr. New* has recently given the name of Xyleutes, the carpenter, to the genus including this insect, instead of Cossus, which it formerly bore, because the latter, being the name of a species, ought not to have been applied to a genus. The European carpenter-moth, called Bombyx Cossus † by Linnæus, will now be the Xyleutes Cossus; and our indigenous species will be the Xyleutes Robinia, or locust-tree carpenter-moth. The moths of this genus have thick and robust bodies, broad and thickly veined wings, two very distinct feelers, and antennæ, which are furnished on the under-side, in both sexes, with a double set of short teeth, rather longer in the male than in the female. Their tongue is invisible. They give out a strong and peculiar smell, whence they are sometimes called goat-moths by English writers.

Some caterpillars, which eat the leaves of plants, live in cases or long oval cocoons, open at both ends, and large enough for the insects to turn around within them, so as to go out of either end. They do not entirely leave these cases, even when moving from place to place, but cling to them on the inside with the legs of the hinder part of their bodies, while their heads and fore-legs are thrust out. Thus in moving they creep with their six forelegs only, and drag along their cases after them as they go. These cases are made of silk within, and are covered on the outside with leaves, bits of straw, or little sticks. The caterpillars are nearly cylindrical, generally soft and whitish, except the head and upper part of the first three rings, which are brown and hard; they have sixteen legs; the first three pairs are long, strong, and armed with stout claws; the others are very short, consisting merely of slight wart-like elevations provided with numerous minute clinging hooks. When they are about to change their forms their cases serve them instead of cocoons; they fasten them by silken threads to the plant on which they live, stop up the holes

* See "Entomological Magazine," Vol. V. p. 129.

↑ Subsequently named Cossus ligniperda by Fabricius.

in them, and then throw off their caterpillar-skins. The chrysalids are remarkably blunt at the hinder extremity, and are provided with transverse rows of minute teeth on the back of the abdominal rings. The moths, of which there are several kinds produced by these case-bearing caterpillars, differ very much from each other; but, as they all agree in their habits and general appearance while in the caterpillar form, they are brought together in one family called PSYCHADE, the Psychians, from Psyche, a genus belonging to it. The Germans give these insects a more characteristic name, that of sackträger*, that is, sack-bearers, and Hübner called them Canephora, or basket-carriers, because the cases of some of them are made of little sticks somewhat like a wicker basket. The cases of the insects belonging to the European genus Psyche are covered with small leaves, bits of grass or of sticks, placed lengthwise on them. The chrysalis of the male Psyche, pushes itself half-way out of the case when about to set free the moth; the female, on the contrary, never leaves its cocoon, is not provided with wings, and its antennæ and legs are very short. The male Psyche resembles somewhat the same sex of Orgyia, having pretty broad wings, and antennæ that are doubly feathered on the under-side; it has also a bristle and hook to hold the wings together. The cases of Oiketicus †, another and much larger kind of sack-bearer, inhabiting the West Indies and South America, are covered with pieces of leaves and of sticks arranged either longitudinally or transversely. The cases of some of the females, measure four or five inches in length. Some which I received from Cuba were covered with little bits of sticks, about a quarter of an inch long, arranged transversely, and the cases were hung by a thick silken loop or ring to a twig; the lower end of these cases was filled with a large quantity of loose and very soft brownish floss-silk, which completely closed the orifice within. The male Oiketicus resembles a Zeuzera in the form and great length of its body, in the shape of its wings, and in its antennæ, and in both the latter it

* See Germar's "Magazin der Entomologie," Vol. I. p. 19.

+ This name ought to be Eceticus. See Mr. Guilding's description of the insect in the "Transactions of the Linnæan Society," Vol. XV.