to those represented in our figure of the tracks of the Pinebark. beetle on a succeeding page, though larger than those, being PINE. TRUNK. about equal to the width of the track in their length, but less in their width, and having their outer ends evenly rounded. In each of these notches from one to four eggs are placed. And as the beetles mine their way onwards, the fine dust which they form probably becomes strewed along the track behind them. Then, as they travel backwards and forwards in the burrow from time to time, the little stiff hairs with which their bodies. are bearded, serve as a brush to sweep this dust into these lateral openings. Thus the mouths of these notches become filled and the eggs therein covered and concealed from any predaceous insect which may enter the burrow after the parent has completed her work and before the eggs have hatched and the young have mined their way beyond the reach of such enemies. The female continues her operations until her stock of eggs is exhausted, forming a burrow from four to eight inches or more in length. The eggs of this beetle are about 0.025 long, of a broad oval shape and a watery white color. They may be met with in their newly formed burrows beneath the bark the fore part of June. They probably hatch in ten to twenty days, according to the temperature of the atmosphere at this time. The infantile larva is invariably found lying with its back towards the sawdust with which the notch in which it is bred is filled, its mouth being thus brought in contact with the soft innermost layer of the bark at the extremity of the notch-the elastic nature of the sawdust probably aiding in pressing its mouth against its destined nourishment. Thus it has only to part its jaws and close them together again to fill its mouth with food. And by repetitions of this motion a cavity is gradually formed between the bark and the wood, into which its head sinks, and afterwards its body. This cavity consequently takes a direc tion outwards at right angles with the central burrow. And thus the larva eats its way onward until it has obtained its growth, forming hereby a gallery varying in its length from about one to three inches, as the material consumed has been of a quality more or less nutricious, and winding and turning where impediments have been encountered or the track of another larva has been approached. Many of these lateral PINE. YRUNK. galleries, however, end abruptly before they are half completed, the worm having been destroyed by insect enemies or some other casualty. And it is curious to notice how these little creatures respect the territory which is already in possession of another, changing their course to avoid any encroachment thereon; and if one of them finds himself so surrounded and hemmed in by other tracks that it becomes impossible for him to refrain from encountering them, he so shapes his course as to cross his neighbor's road as nearly as possible at right angles instead of obliquely, thus intruding thereon as little and for as short a time as possible. Sometimes also two females happen to excavate their galleries parallel with each other, and so near that no adequate space remains between them for their young to mine their burrows, the beetles having been unaware of their proximity, no doubt, until too much labor had been expended to admit either one to abandon the ground and go elsewhere. In such cases the eggs are all placed along the outer side of each gallery, and thus the larvæ all mine their way outward in opposite directions to each other. The larva is a plump soft white worm, broadest anteriorly, and with its body bent into an arch or having its tail turned partially inward under the breast. By transverse impressed lines it is divided into thirteen segments, the head being counted as one. Its head is polished and white, at least during the first periods of its life, with its maudibles chestnut brown, and no indications of eyes, and no feet, but with their places supplied by two small round retractile teat-like protuberances on the under side of each of the three segments next to the head. Having completed their growth, they sink themselves into the wood to repose during their pupa state. The small round hole which they perforate in the wood for this purpose, is seen at or near the outer end of each burrow in which the worm has lived to reach maturity. The pupa resembles the perfect insect in its size and shape, with the rudimentary legs and wings enclosed in sheaths and appressed to the outer surface of its body in front. After taking on its perfect form it perforates a small round hole through the bark and comes out from the tree. PINE. TRUNK. This and the other bark beetles of the pine have numerous insect enemies which wage incessant war upon them. Various species of small beetles pertaining to the families Staphylinida, Histerida, &c., are always to be met with under the loose worm-eaten bark of pines, and M. Perris has ascertained that these insects resort to this situation for the purpose of rearing their young, their larvæ being predaceous and subsisting upon the larvæ and pupa of the bark beetles. 243. FINE-WRITING BARK-BEETLE, Tomicus calligraphus, Germar. Under the bark of the pitch pine and other species of pine, mining long and often zigzag tracks lengthwise of the tree, these tracks having short, coarse, irregular branches; a chestnut-brown bark-beetle 0.18 to 0.22 long, cloathed with numerous yellowish gray hairs, its thorax rough anteriorly from close elevated points, and punctured posteriorly, its wing covers with rows of coarse punctures, their tip broadly excavated as though with a gougechisel, the surface of this excavation rough from coarsish punctures, and its margin on each side with five or six small unequal teeth. Appearing mostly in the month of May. This species was originally named exesus, or the excavated bark-beetle, in allusion to the tips of its wing covers, in the old Catalogue of Rev. F. V. Melsheimer, under which name a short account of it was published by Mr. Say, in the year 1826. Germar, however, had described it two years before, under the name calligraphus, meaning elegant writer, which name it must retain, although not happily chosen, the tracks which this beetle forms under the bark being coarse, irregular, confused, and far less beautiful than those of many of the species of this genus. It is in the pitch pine that this beetle mostly occurs in the State of New-York, but I have also met with it in the limbs of aged white pines, and farther south it is common in the yellow pine. Its burrow is somewhat like that of the preceding species, consisting of a single long furrow extending lengthwise of the tree or limb, from six to twelve inches in length, but it is less straight in this species, being usually curved more or less, and according to accounts it is often perfectly zigzag. The same notches are formed along its sides as noticed in the foregoing [AG. TRANS.] 46 species, in which the eggs are deposited; but the lateral burrows which branch from the central one have no regularity whatever to them, being given off sometimes obliquely and sometimes at right angles, sometimes abruptly widening into a broad irregular flat cavity, and sometimes continuing of the same width through their whole length, either straight, irregularly wavy or tortuous, turning here and there, wherever an unoccupied space occurs into which they can be extended. These branches are usually of the same width with the central gallery, and like it are furrowed equally deep in the outer surface of the wood and the inner surface of the bark. The pupa state is passed in a cell excavated in the bark, and not in the wood, as in the foregoing species, and when changed into a beetle this cell is extended onwards through the bark for the escape of the insect. Being a larger species than the preceding the galleries which it excavates, and the holes it perforates through the bark, are proportionally larger. Several dead individuals may usually be found in the galleries of this as of the other species. 244. PINE BARK-BEETLE, Tomicus Pini, Say. From a common centre excavating several broad shortish galleries lengthwise of the trunk in opposite directions, resembling the spread fingers of a hand; a bark-beetle very similar to the preceding but of a smaller size, measuring only 0.15 in length, and with but four small teeth on each side of the concave declivity at the tips of its wing covers, and usually showing more or less distinctly an impressed line along the middle of the hind part of its thorax. The tracks formed by this insect are so different from those of the other species that they are recognised at a glance. They occur under the bark of old trees of the white pine, and have some resemblance to the fingers of a hand spread apart, or to the track of a bird. From a common centre they run off in opposite directions up and down the tree, lengthwise of the grain, moderately diverging or nearly parallel with each other, appearing, when the bark is stripped off, like linear grooves in the outer surface of the wood and inner surface of the bark. They |