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STINGERS, AND PIERCERS. — HABITS OF SOME OF THE HYMENOPTERA. — Saw
FLIES, AND SLUGS. ELM Saw-Fly. Fir Saw-Fly. VINE Saw-Fly. RoseBUSH Slug. PEAR-TREE Slug.– HORN-TAILED Wood-Wasps. — GALL-FLIES. - CHALCIDIANS. BARLEY INSECT AND JOINT-WORM.
Bees, wasps, ants, saw-flies, and ichneumon-flies, of many different kinds, together with other insects, unknown by any common names in the English language, belong to the order HYMENOPTERA. Their wings are four in number, are traversed by a few, branching veins, and are more or less transparent, or of a thin and filmy texture, as expressed by the name of the order, which signifies membranaceous wings. They fly swiftly, and are able to keep on the wing much longer than any other insects, because their bodies are light, and compact, and their wings very thin, narrow, and withal very strong. They have four nippers or jaws; the upper pair being horny, stout, and fitted for biting or cutting; the lower are longer and softer, and, with the lower lip, which they cover, form a kind of beak or sucker. Their antennæ vary in form and length; but are most often cylindrical, and of equal thickness to the end. The males have no weapons of offence or defence except their jaws. The females are armed with a venomous sting, concealed within the end of the hind body, or are provided with a piercer, of some sort, for boring or sawing the holes wherein their eggs are deposited. Hence the insects of this order may be divided into two groups, Stingers, and Piercers. Though both of them undergo a complete transformation in coming to maturity, they differ from each other in the early states of their existence. The young of all the stinging Hymenoptera are soft, white, and maggot-shaped, and are without legs; some of those of the Piercers have the same form, but the others more nearly resemble grubs and caterpillars, having a horny head, and six jointed legs, and some of them numerous fleshy proplegs, besides. The latter, when food fails them in one place, are able to creep to another, and can look out for themselves a proper place of shelter, wherein to go through with their transformations. The others are exceedingly helpless, and depend wholly upon the instinctive foresight of their parents, or the daily care of attentive nurses, for their food and habitations. When fully grown, nearly all of these young insects spin oblong oval cocoons, wherein they change to chrysalids, and finally to winged insects. A few, however, never obtain wings in the adult state; but these are mostly certain neuter and female ants, the males of which possess wings. With the exception of the white ants, belonging to another order, it is only among Hymenopterous insects that we find certain individuals constantly barren, and hence called neuters. These form the principal part of those communities of bees, of wasps, and of ants, that unite in making a habitation for the whole swarm, and in providing a stock of provisions for their own use, and for that of their helpless brood; and nearly or quite all the labor falls upon these industrious neuters, whose care and affection for the young, which they foster and shelter, could not be greater were they their own offspring.
Hymenopterous insects love the light of the sun; they take wing only during the daytime, and remain at rest in the night, and in dull and wet weather. They excel all other insects in the number and variety of their instincts, which are wonderfully displayed in the methods employed by them in providing for the comfort and the future wants of their offspring. In the introductory chapter some remarks have already been made on their habits and economy; and the limits of this work will not allow me now to enlarge upon them. I shall not, therefore, attempt to show how admirably the Hymenoptera are fitted, in the formation of all their parts, for their appointed tasks. If any of my readers are curious to learn this, and to witness for themselves the various arts, resources, and contrivances resorted to by these insects, let them go abroad in the summer, and watch them during their labors. They will then see the saw-fly making holes in leaves with her double key-hole saws, and the horn-tail boring with her auger into the solid trunks of trees;—they will not fail to observe and admire the untiring scrutiny of the ichneumonflies, those little busy-bodies, for ever on the alert, and prying into every place to find the lurking caterpillar, grub, or maggot, wherein to thrust their eggs;- the curious swellings produced by the gall-Aies, and inhabited by their young;-the clay cells of the mud-wasp, plastered against the walls of our houses, each one containing a single egg, together with a large number of living spiders, caught and imprisoned therein solely for the use of the little mason's young, which thus have constantly before them an ample supply of fresh provisions;the holes of the stump-wasp, stored with hundreds of horseflies for the same purpose; the skill of the leaf-cutter bee in cutting out the semicircular pieces of leaves for her patchwork nest;—the thimble-shaped cells of the ground-bee, hidden, in clusters, under some loose stone in the fields, made of little fragments of tempered clay, and stored with bee-bread, the work of many weeks for the industrious laborer;— the waxen cells made by the honey-bee, without any teaching, upon purely mathematical principles, measured only with her antennæ, and wrought with her jaws and tongue;—the watertight nests of the hornet and wasp, natural paper-makers from the beginning of time, who are not obliged to use rags or ropes in the formation of their durable paper combs, but have applied to this purpose fibres of wood, a material that the art of man has not yet been able to manufacture into paper;the herculean labors of ants in throwing up their hillocks, or mining their galleries, compared wherewith, if the small size of the laborers be taken into account, the efforts of man in his proudest monuments, his pyramids and his catacombs, dwindle into insignificance. These are only a few of the objects deserving of notice among the insects of this order; many others might be mentioned, that would lead us to observe with what consummate skill these little creatures have been fashioned, and how richly they have been endowed with instincts, that never fail them in providing for their own welfare, and that of their future progeny.
Comparatively speaking, there are not many of the Hymenoptera which are actually or seriously injurious to vegetation. Those which I propose now to describe are not provided with venomous stings, and, consequently, are to be included among the Piercers.
Such are the saw-flies (TENTHREDINIDÆ), insects that are found on the leaves of plants, and live almost entirely on vegetable food. They are the least active of the Hymenoptera, are sluggish in their habits, fly heavily and but little, and do not attempt to escape when touched. Most of them are rather short and somewhat flattened. They have a broad head, which, seen from above, appears transversely square. The hind body is not narrowed to a point where it joins the thorax, but is as broad as the latter, and is closely united to it. The antennæ are generally short; but they vary much in form; in many species they are threadlike and slightly tapering; in some, thickened or knobbed at the end; more rarely they end suddenly with a few very small joints, much more slender than the rest; they are feathered in some males, and notched in the other sex; and sometimes they are forked, or divided into long branches. Their wings cross and overlap each other, and cover the back horizontally when closed. But the most striking peculiarity of these insects consists in the double saws wherewith the females are provided. These are lodged in a deep chink under the hinder part of the body, like the blade of a penknife in its handle, and are covered by two, narrow, scabbard-like pieces. The saws are two in number, placed side by side, with their ends directed backwards, and are so hinged to the under side of the body that they can be withdrawn from the chink, and moved up and down when in use. They vary in their form, and in the shape of their teeth, in different kinds of saw-flies; but they generally curve upwards and taper towards the end, and are toothed along the lower or convex edges. Each of the saws, like a carpenter's fine saw, has a back to steady it; the blade, however, is not fastened to the back, but slides backwards and forwards upon it. Moreover, the saw-blade is not only toothed on the edge, but is covered, on one side, with transverse rows of very fine teeth, giving to it the power of a rasp, as well as that of a saw.
The female saw-flies use these ingeniously contrived tools to saw little slits in the stems and leaves of plants, wherein they afterwards drop their eggs. Some, it appears, lay their eggs in fruits; for Mr. Westwood discovered their young within apples that had fallen from the trees before they had grown to the size of walnuts. The wounds made in plants by some kinds of saw-flies swell, and produce galls or knobs, that serve for habitations and for food to their young. The eggs, themselves, of all these flies, are found to grow, and increase to twice their former size after they are laid, probably by absorbing the sap of the plant through their thin shells.
Most of the larvæ or young of the saw-flies strikingly resemble caterpillars, being usually of a cylindrical form, of a greenish color, and having several pairs of legs. Hence they are sometimes called false caterpillars. With the exception of such as belong to the genera Lyda and Cephus, in which the legs are only six, and the proplegs are entirely wanting, these false caterpillars have a greater number of legs than true caterpillars, being provided with from eighteen to twentytwo; but their proplegs have not the numerous little hooks that arm those of caterpillars. They have the means of spinning silk from their lower lips, but not often in any great quantity. They are mostly naked and without hairs; a few have forked prickles on their backs; some are covered with a white flaky substance, that easily rubs off; and others have a dark colored slimy skin, which has caused them to be called slugs or slug-worms. They shed their skins about four times, and, after the last moulting, often materially change in appearance. Not only do these insects resemble caterpillars in their forms, but they have nearly the same habits. They are generally found on the leaves of plants, which they devour. Many kinds are altogether solitary; a few live together in swarms, under silken webs, which they spin for a common place of shelter; others are found also in swarms, but without any webs over them, and, when disturbed, they throw up their heads and tails, in a very odd way; some roll up leaves, and live in the hollow thus formed, like the Tortrices; others make portable cases of bits of leaves, which they carry about on