corresponding, for the most part, in situation, with the ears of other animals, and supposed to be connected with the sense of hearing, of touch, or of both united. The antennæ are very short in larvæ, and of various sizes and forms in other insects.

The mouth of some insects is made for biting or chewing, that of others for taking the food only by suction. The biting-insects have the parts of the mouth variously modified to suit the nature of the food; and these parts are, an upper and an under lip, two nippers or jaws on each side, moving sidewise, and not up and down, and four or six little jointed members, called palpi or feelers, whereof two belong to the lower lip, and one or two to each of the lower jaws. The mouth of sucking-insects consists essentially of these same parts, but so different in their shape and in the purposes for which they are designed, that the resemblance between them and those of biting-insects is not easily recognized. Thus the jaws of caterpillars are transformed to a spiral suckingtube in butterflies and moths, and those of maggots to a hard proboscis, fitted for piercing, as in the mosquito and horse-fly, or to one of softer consistence, and ending with fleshy lips for lapping, as in common flies; while in bugs, plant-lice, and some other insects resembling them, the parts of the mouth undergo no essential change from infancy to the adult state, but are formed into a long, hard, and jointed beak, bent under the breast when not in use, and designed only for making punctures and drawing in liquid nourishment.

The parts belonging to the thorax are the wings and the legs. The former are two or four in number, and vary greatly in form and consistence, in the situation of the wingbones or veins, as they are generally called, and in their position or the manner in which they are closed or folded when at rest. The under-side of the thorax is the breast, and to this are fixed the legs, which are six in number in adult insects, and in the larvæ and pupae of those that are subject

only to a partial transformation. The parts of the legs are the hip-joint, by which the leg is fastened to the body, the thigh, the shank (tibia), and the foot, the latter consisting sometimes of one joint only, more often of two, three, four, or five pieces (tarsi), connected end to end, like the joints of the finger, and armed at the extremity with one or two claws. Of the larvæ that undergo a complete transformation, maggots and some others are destitute of legs; many grubs have six, namely, a pair beneath the under-side of the first three segments, and sometimes an additional fleshy prop-leg under the hindmost extremity; caterpillars and false caterpillars have, besides the six true legs attached to the first three rings, several fleshy prop-like legs, amounting sometimes to ten or sixteen in number, placed in pairs beneath the other segments.

The abdomen, or hindmost, and, as to size, the principal part of the body, contains the organs of digestion, and other internal parts, and to it also belong the piercer and the sting with which many winged or adult insects are provided. The piercer is sometimes only a flexible or a jointed tube, capable of being thrust out of the end of the body, and is used for conducting the eggs into the crevices or holes where they are to be laid. In some other insects it consists of a kind of scabbard, containing a central borer, or instruments like saws, designed for making holes wherein the eggs are to be inserted. The sting, in like manner, consists of a sheath enclosing a sharp instrument for inflicting wounds, connected wherewith in the inside of the body is a bag of venom or poison. The parts belonging to the abdomen of larvæ are various, but are mostly designed to aid them in their motions, or to provide for their respiration.

An English entomologist has stated, that, on an average, there are six distinct insects to one plant. This proportion is probably too great for our country, where vast tracts are covered with forests, and the other original vegetable races still hold possession of the soil. There are above 1,200

flowering plants in Massachusetts, and it will be within bounds to estimate the species of insects at 4,800, or in the proportion of four to one plant. To facilitate the study of such an immense number, some kind of classification is necessary; it will be useful to adopt one, even in describing the few species now before us. The basis of this classification is founded upon the structure of the mouth, in the adult state, the number and nature of the wings, and the transformations. The first great divisions are called orders, of which the following seven are very generally adopted by naturalists.

1. COLEOPTERA (Beetles). Insects with jaws, two thick wing-covers meeting in a straight line on the top of the back, and two filmy wings, which are folded transversely. Transformation complete. Larvæ, called grubs, generally provided with six true legs, and sometimes also with a terminal propleg; more rarely without legs. Pupa with the wings and the legs distinct and unconfined.

Fig. 1.

Many of these insects, particularly in the larva state, are very injurious to vegetation. The tiger-beetles (Cicindelada*), the predaceous ground-beetles (Carabida), the diving-beetles (Dytiscide), the lady-birds (Coccinellada), and some others, are eminently serviceable by preying upon caterpillars, plant-lice, and other noxious or destructive insects. The water-lovers (Hydrophilida), rove-beetles (Staphylinida), carrion-beetles (Silphada), skin-beetles (Dermestada, Byrrhida, and Trogida), bone-beetles (some of the Nitidulada and Cleride), and various kinds of dung-beetles (Sphæridiadæ, Histerida, Geotrupidæ, Copridida,† and Aphodiada†), and clocks (Pimeliada and Blaptida), act the useful part of scavengers, by removing carrion, dung, and other filth, upon which alone they and their larvæ subsist. Many * See the Catalogue of Insects appended to Professor Hitchcock's Report on the Geology, Mineralogy, Botany, and Zoology of Massachusetts. 2d edit. Amherst. 1835.

Tenebrio molitor.

(Meal-worm.)

Larva.

8vo.

† All the Scarabæide of my Catalogue, from Ateuchus to Geotrupes inclusive, to which may be added many included in the genus Scarabæus.

Fig. 2.

Pupa.

Coleoptera (some Staphylinida and Nitidulada, Diaperidida, some Serropalpida, Mycetophagidæ, Erotylidæ, and Endomychida) live altogether on agarics, mushrooms, and toadstools, plants of very little use to man, many of them poisonous, and in a state of decay often offensive; these fungus-eaters are therefore to be reckoned among our friends. There are others, such as the stag-beetles (Lucanida), some spring-beetles (Elateridæ), darkling-beetles (Tenebrionida), (Figs. 1-3,) and many bark-beetles (Helopida, Cistelada, Serropalpida, Edemerada, Cucujada, and some Trogositada), which, living under the bark and in the trunks and roots of old trees, though they may occasionally prove injurious, must on the whole be considered as serviceable, by contributing to destroy and reduce to dust plants that have passed their prime and are fast going to decay. And, lastly, the blistering-beetles (Cantharidida) have, for a long time, been employed with great benefit in the healing art.

Fig. 3.

Imago.

2. ORTHOPTERA (Cockroaches, Crickets, Grasshoppers, &c.). Insects with jaws, two rather thick and opaque upper wings, overlapping a little on the back, and two larger, thin wings, which are folded in plaits, like a fan. Transformation partial. Larvæ and pupæ active, but wanting wings.

All of the insects of this order, except the camel-crickets (Mantida), which prey on other insects, are injurious to our household possessions, or destructive to vegetation.

3. HEMIPTERA (Bugs, Locusts, Plant-lice, &c.). Insects with a horny beak for suction, four wings, whereof the uppermost are generally thick at the base, with thinner extremities, which lie flat, and cross each other on the top of the back, or are of uniform thickness throughout, and slope at the sides like a roof. Transformation partial. Larvæ and pupa nearly like the adult insect, but wanting wings.

The various kinds of field and house bugs give out a strong and disagreeable smell. Many of them (some Pentatomadæ and Ly

gaida, Cimicidæ, Reduviada, Hydrometrada, Nepada [Plate I. Fig. 1, Nepa apiculata], and Notonectada) live entirely on the juices of animals, and by this means destroy great numbers of noxious insects; some are of much service in the arts, affording us the costly cochineal, scarlet grain, lac, and manna; but the benefits derived from these are more than counterbalanced by the injuries committed by the domestic kinds, and by the numerous tribes of plant-bugs, locusts or cicada, tree-hoppers, plant-lice, bark-lice, mealy bugs, and the like, that suck the juices of plants, and require the greatest care and watchfulness on our part to keep them in check.

4. NEUROPTERA (Dragon-flies, Lace-winged flies; Mayflies, Ant-lion, Day-fly, White Ants, &c.). Insects with jaws, four netted wings, of which the hinder ones are the largest, and no sting or piercer. Transformation complete, or partial. Larva and pupa various.

The white ants, wood-lice, and wood-ticks, (Termitida and Psocida,) the latter including also the little ominous death-watch, are almost the only noxious insects in the order, and even these do not injure living plants. The dragon-flies, or, as they are commonly called in this country, devil's-needles (Libellulada), (Figs. 4, 5,) (Plate I. Fig. 2, Agrion basalis,) prey upon gnats and mosquitoes; and their larvæ and pupa, as well as those of the day-flies (Ephemerada), semblians (Semblidida), and those of some of the May-flies, called caddis-worms (Phryganeada), (Fig. 6,) all of which live in the water, devour aquatic insects. predaceous habits of the ant-lions (Myrmeleontida), (Fig. 7,) have been often described. The lace-winged flies (Hemerobiada), (Fig. 8,) in the larva state, live wholly on plant-lice, great numbers of which they destroy. The mantispians (Mantispada), and the scorpion-flies (Panorpada), are also predaceous insects.

The

5. LEPIDOPTERA (Butterflies and Moths). Mouth with a spiral sucking-tube; wings four, covered with branny scales. Transformation complete. The larvæ are caterpillars, and have six true legs, and from four to ten fleshy prop-legs.