or breast-plate, and is divided into three parts, the prosternum or fore breast-plate; the mesosternum or middle breast-plate; and the metasternum or hind breast-plate. Each of these parts has a side piece called the episternum; so that there is an episternum of the prothorax; an episternum of the mesothorax; and an episternum of the metathorax; all of which are labelled in the figure. Directly behind each episternum is a smaller piece called the epimeron. These are indicated in the figure by stars; three stars marking the epimeron of the prothorax; two stars the epimeron of the mesothorax; and one star the epimeron of the metathorax. The epimeron of the mesothorax is very narrow in Harpalus, and scarcely distinguishable without the aid of a lens; but

in a part of the long-horned beetles (Saperda, etc.) and in some others, it is considerably wider, and affords valuable characters in classification. The trochanters, or little joints at the base of the thighs, are marked TR in the figure, except the large hind trochanters, where the name is printed in full. Behind the metasternum, and extending outwardly from the hind coxæ is a narrow piece marked CX. P. This is the hind coxal plate. This is a very narrow piece in Harpalus, but in some of the serricorn beetles (Buprestida and Elaterida), it is much wider, and furnishes important generic characters; and in Haliplus, a genus of water beetles, it is excessively dilated. The other parts are sufficiently named in the figure.

The antennæ of the Coleoptera are usually eleven jointed and of moderate length, but they are subject to much variation both in length and form, as will appear in the descriptions of the different families. The subjoined figures show their most common variations, and the names by which they are designated. These forms have been more particularly described on a former page, when treating of insects in general.

Explanation.-1, filiform or thread-shaped; 2 and 3, serrate or saw-toothed; 4, pectinate or combtoothed; 5, capitate or knobbed; 6, 7, 8, clavate or club-shaped; 9 and 10, lamellate or plated.

The palpi, or little jointed appendages to the mouth, also sometimes furnish important characters in classification. They vary chiefly in the shape of the termínal joint, which is sometimes much narrower than the others, when it is called acicular or needle-shaped, and sometimes much widened, so as to be in the form of a triangle or of a half moon, or hatchet.

As the terms large, small, and medium-sized are often used in speaking of insects, and as these words vary considerably in force, when used in different relations, we give below their average meaning when applied to the Coleoptera:

An inch or more in length,

Three-quarters of an inch,
Half an inch,

Quarter of an inch,

One-eighth of an inch or less,

Very large.
Large.

Medium.

Small.

Very small.

The intermediate sizes are expressed by such phrases as, rather large, rather small, or a little above, or a little below the medium, etc. This standard applies only when speaking of any one group of beetles as compared with the Coleoptera generally. The same expressions will

necessarily vary in force when applied to the species of a particular group as compared with each other, accordingly as the species of that group are large or small as compared with the rest of the order; that is to say, a small species of a group of generally large-sided insects, may be larger than a large species of a small-sized group.

LARVÆ AND PUPÆ.

The larva of the Coleoptera are usually soft whitish grubs; naked, or with a few scattered hairs; with a mandibulate mouth not very unlike that of the perfect insects; usually furnished with six short feet and a single terminal proleg, but sometimes wholly footless. They live in secluded situations, sometimes in the ground, but oftener in the wood or under the bark of decaying trees, or in putrescent animal substances, and not unfrequently in nuts and seeds, and in the pulp of fruits. They are rarely found exposed to the light of day, and therefore they never exhibit the beauty of coloration, nor the variety of clothing which gives so much interest to the study of the caterpillars, properly so called, which are the larvæ of the moths and butterflies. The larvae of most of the families of Coleoptera are now pretty well known, but owing to the circumstances just mentioned, they have generally received but little attention from entomologists compared with that which has been bestowed upon the perfect insects. The larvæ of the several families will be more particularly described in their proper connections.

The pupa are never inclosed in cocoons, but the larvæ, before changing, simply form cells by turning themselves round and round in the earth or rotten wood, in which they usually undergo their metamorphoses. The legs are free, that is not concealed from view under a pupa case, but they are not used, the insects being dormant and motionless during this stage of their existence.

THE COLEOPTERA FROM A PRACTICAL POINT OF VIEW.

In order to show more clearly the connection between scientific and practical entomology, in classifying the Coleoptera we have taken the food-habits of the several species as the basis of classification, it being in the nature of their food, and their methods of obtaining it, that insects come into the most important relationship to mankind, whether of an injurious or a beneficial character. We refer to the Coleoptera particularly, because they exhibit a much greater diversity of food-habits than any of the other orders of insects. Indeed this principle of classification is of value just in proportion as such diversity exists; and where it is very limited, as especially in the great order of Lepidoptera, it ceases to be available. Even in classifying the Coleoptera upon this basis, and at the same time paying the necessary respect to structural

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considerations, we are sometimes compelled to place insects of similar food-habits in several different, and sometimes remote, tribes. The wood-boring beetles, for example, constitute three distinct tribes, designated as the saw-horned borers (Buprestida); the long-horned borers (Cerambycida); and the short-horned borers (Scolytidæ). There are likewise four distinct families of fungus-beetles, found respectively in each of the four tarsal sections. But notwithstanding such instances as these, the Coleoptera admit of a very interesting, useful, and, in the main, natural classification in accordance with the nature of their food. As compared with the other orders of insects the Coleoptera are surpassed only by the Lepidoptera in the extent of their injuries to cultivated crops; and indeed they are so nearly equal to the latter in this respect, that there may be a doubt which takes the precedence; and it is true of either of these two orders, that, with the exception of the other, it includes a greater number of injurious species than all the other orders of insects combined. The great destructiveness of the Lepidoptera is readily explained by the nature of their food, nearly all their larvæ, commonly known as caterpillars, subsisting upon plant-food, and mostly in a fresh and growing state. The Coleoptera, on the contrary, embraces, in addition to the plant-eating species, extensive tribes of predaceous and scavenger beetles, which are indirectly of incalculable benefit to mankind.

In studying the bearing of scientific upon practical entomology, nothing perhaps is more important than to trace the connection of the external structure of insects with their habits, and especially with the nature of their food; since we are thus enabled, to a certain extent, to determine the habits of an insect by simply observing the form and structure of its visible parts. We are able to lay down some general rules of this kind with respect to the Coleoptera, though most of them are subject to important exceptions. In order not to give too much space to this part of the subject, we will limit our observations to two of the most important and prominent organs, the antennæ, and the feet, or tarsi.

All predaceous beetles have filiform antennæ except the lady-bugs or Coccinellidæ.

All the scavenger beetles have strongly clavate or knobbed antennæ, except the short-winged scavengers or Staphylinidæ.

All the leaf-eating beetles have filiform or nearly filiform antennæ, except the herbivorous Lamellicorns (Rutelida and Melolonthida.) All fungus-eating beetles have the antennæ more or less strongly clavate.

The feet of the Coleoptera are of two principal kinds; first, simple feet, in which the joints are slender, and of about the same width

throughout, and clothed only with somewhat scattered bristles; and secondly bi-lobed feet, in which the joints are somewhat widened and depressed, with the last joint but one wider than the others, and divided into two lobes, between which the last joint is inserted, and all of them clothed beneath with densely crowded short stiff hairs, of the same length, so as to resemble a brush; sometimes also compared to a piece of sponge.

As a general rule, beetles with simple feet reside upon the ground, or under the bark of dead trees, or in other decomposing matter, and are either carnivorous or rypophagous (filth eating) in their habits; and those which have bilobed and spongy feet live upon the foliage of trees and other plants, this structure of the feet seeming to be especially adapted to enabling them to adhere to the surface of leaves; and accordingly most of these insects are herbivorous.

But this general statement is subject to important exceptions. Some of the lamellicorn beetles (Melonthida, Rutelidæ, etc.) have simple feet and yet feed upon the foliage of trees; but these insects do not run over the leaves, but simply cling to them with their sharp claws, whilst feeding.

So, also, some carnivorous beetles (Telephorida and Coccinellida), which pursue their prey over the foliage of trees, have their feet bilobed and spongy.

It is an interesting circumstance that those insects (Melolonthidæ, etc.) which only cling to the foliage by their claws, do not breed upon the trees, but pass their larval period under ground, subsisting upon roots or other subterranean matters, and only visit the trees for the sake of feeding; whereas the true Phytophaga, with spongy feet (Chrysomelida and their allies) live upon the plants upon which they feed, through all the stages of their existence.

It is also a curious coincidence that the insects first mentioned, which only visit the trees occasionally for the purpose of feeding, do so only by night; whilst the genuine Phytophaga (plant eaters) are diurnal in their habits.

There is another partial but important exception to the rule above laid down, as respects the males of many carnivorous beetles, which have some of the joints of their anterior feet much widened and brushed underneath; but here the last joint but one is not bilobed, and the brush is usually confined to the anterior pair of feet, rarely extending to the middle pair, and never to the hind ones; besides being limited exclusively to the males.

Whilst some of the other orders of insects excel the Coleoptera in the perfection of their instincts, no other order can be compared with them in the diversity of their food, and their corresponding habits and organization. Indeed the Coleoptera combine, to a great extent, the food. Vol. IV-53