Beetle, a very numerous and well known order of insects, constituting the coleoptera. They have usually 4 wings: 2 membranous, the organs of flight, filmy and folded transversely; and 2, anterior and superior to these, of a harder consistence, protecting the former, and called elytra. They all have mandibles and jaws. The head varies greatly both in size and form in the different tribes; it presents 2 antennae, of various forms, of which the joints are generally 11 in number; the eyes are 2, and compound; they have no simple eyes, according to Latreille. The mouth consists of a labrum; 2 mandibles, usually of a horny consistence; 2 jaws, each one having or 2 palpi; and a labium of 2 pieces, accompanied by 2 palpi. The anterior segment of the thorax, or the corslet, which is in front of the wings, is larger than the other two segments, and is free in its movements; it supports only the first pair of legs; the other segments are united together, and nearly immovable; the mesothorax supports the second pair of legs and the elytra; the membranous wings and the third pair of legs are attached to the third and last segment. The elytra and wings originate from the lateral and upper portions of the segments.
The former are of a firm consistence, almost crustaceous, and, in a state of rest, are applied horizontally one against the other along their internal edge; they almost always conceal the true wings, and are generally as long as the body; in the act of flight they are usually extended, though in some species destitute of true wings they are united on the dorsal suture; in the wingless genera the elytra are always found. The abdomen is sessile, or united to the chest by its greatest breadth, composed of 6 or 7 rings, membranous above, where it is protected by the elytra, and of a more horny consistence below. In the males the anterior pair of legs are often stronger, and the tarsi broader, than in the females. All the coleoptera masticate, and are accordingly provided with instruments proper for cutting and triturating their food; the salivary glands are quite rudimentary, and few in number; the digestive canal varies in length according to the habit of life, but it generally is much longer than the body. The sexes are separate, and the act of reproduction is a true sexual connection. The organs of respira-tion are stigmata along the sides of the body, and tracheae pervading all parts of the system.
The abdomen encloses a fatty tissue, apparently connected with nutrition, which causes many of these insects to be eagerly sought for as food by the savage tribes of the old world. They undergo a complete metamorphosis; and the larvae or grubs are generally soft-bodied, and provided with 6 legs; it is in this state that they are so destructive to vegetation. The males perish soon after the sexual union, and the females die shortly after the eggs have been deposited. - The coleoptera have been variously divided by different authors; the divisions of Latreille, according to the number of the joints in the tarsi, have been generally adopted by naturalists. These divisions are the following: 1, pentamera, having 5 joints on each foot; 2, heteromera, having 5 joints to the anterior 2 pairs of feet, and 4 joints to the posterior pair; 3, tetramera, having 4 joints to all the feet; 4, trimera, having no more than 3 joints to the feet. Though this system is artificial, and in many points very defective, it is still sufficient to give a clear idea of this very complex order. Latreille makes 20 families.
The pentamera include: 1. The carnivora, whose varied species all agree in being exceedingly voracious; they are both terrestrial and aquatic; the former have been divided into the tribes cicin-deletce and carabici; the latter constitute the tribe hydrocanthari. The cicindelce are very beautifully ornamented, of light and active forms, quick in their motions, darting on their insect prey, which they devour alive; they prefer light and sandy districts exposed to the sun; they are extensively distributed over the earth; the larvae are of a forbidding appearance and extremely voracious, seizing any insect which passes the openings of their subterranean holes. All the carabici, in the grub and perfect state, feed on living prey; they emit a fetid liquid when pursued, and are for the most part agile runners; many have no true wings; they conceal themselves in the earth or under stones and the bark of trees.
1. Digestive apparatus. 2. Mouth. 8. Thorax. 4. Fore leg. 5. Hind leg. 6. Nervous system.
Bombardier Beetle (Brachinus crepitans).
This is a very numerous tribe, and its study is difficult. Some of the most interesting genera are carabiis, scarites, harpalus, brachinus, fe-ronia, etc. Among the cardbidm or ground beetles, many of which eject a fetid fluid for defensive purposes, may be mentioned the bombardier beetle (brachinus), of which there are several species in both hemispheres, varying in length from one eighth to half an inch. The wing covers and lower part of abdomen are bluish black; the rest of the insect, including the long and narrow head and thorax, legs, and antennae, reddish. The species of brachi-nv8, and of the allied genus aptinvs, have received the above name from their habit of projecting from the anus, with an explosive puff, a fine acid spray, to the distance of several inches, so irritating to the eyes and abraded skin as to cause severe smarting, and discoloring the cuticle as if by an acid; the fluid is very volatile, and of a pungent odor. They are carnivorous in all their stages, and not injurious to vegetation. The larger tropical species are the most brilliant.
The hydrocan-thari, or swimming beetles, include the genera dytucus and gyrinus; the feet are adapted for swimming, being compressed and ciliated; they live in the fresh lakes and marshes and quiet streams of all countries, and they pass their first and final stages in the water. The dytisci can live on the land and also can fly; they vary in size from 1 1/2 inch to 1/4 of an inch in length; they are carnivorous and voracious, and can remain a long time under water in pursuit of their prey; they swim on the surface with great rapidity. The gyrini are smaller, and may be found in troops on the surface of still waters, darting about with surprising agility; they can see in the water and in the air at the same time; they can fly well, though they swim better; the eggs are deposited on the leaves of aquatic plants. This family is useful in destroying noxious and predaceous insects and grubs. 2. The brachelytra have but one palpus in the jaws, or four in all; the wing cases are shorter than the body, which is narrow and elongated; the head is large and flat, the mandibles strong, the antennae short; they live in moist earth, on dung and other ex-crementitious matters, and most of all in decaying animal carcasses; they are courageous and strong, running or flying with the greatest facility; they destroy insects with eagerness.
This family is composed entirely of the old and vaguely determined Linnaean genus staphy-Unu8. The larvae live in the same situations as the perfect insects. The family are very useful natural scavengers. 3. The serricornes have elytra covering the abdomen, and antennae equal throughout, dentated, saw-like or fanlike. Among the most interesting genera is buprestis, many of whose species are very large and exceedingly brilliant; these walk very slowly, but are excellent flyers; they are most numerous in warm climates, and live generally in wood. The genus elater is remarkable for the shortness of the legs, and for the faculty it has of changing from a supine position to its feet by springing into the air by means of a spine on its praesternum; the species are found in flowers or plants, and on the ground; some of the American species, as the E. noctiluciis, are phosphorescent, and are called fireflies. The genus lampyris also is interesting, as containing the phosphorescent species whose females go by the name of glowworms. The genus telephorw is noted as furnishing the species which are occasionally taken up by high winds, and deposited in distant regions, causing the so-called insect showers. The tick of the death-watch is produced by a species of anobium, living in decaying wood.
The larvae sometimes cause great destruction of valuable timber. 4. The clavicornes have the antennae thickened or knob-shaped at the end; they live chiefly on animal substances. The genus liister feeds on decaying and ex-crementitious matters. The genus necropjhoras is noted for its habit of interring small animals, such as mice and moles, for the purpose of depositing its eggs in the decaying carcass; this they do by removing the earth beneath the body, which falls into the hollow; their sense of smell must be extremely acute. The genus 8ilpha also prefers putrefying animal substances. The genera dermestes and anthrenus, in their larva state, are perfect pests to the naturalist, as they devour every animal substance accessible in his cabinet; the action of heat, usually employed to destroy them, is nearly as destructive as the insects. 5. The palpicornes resemble the preceding family in the shape of the antennae, composed of only nine joints, and the feet in most of the genera are formed for swimming. The genus hydro-philus is carnivorous and voracious, frequenting fresh water and marshes, swimming well, but not so rapidly as dytiscus; their larvae destroy great numbers of aquatic insects and water snails; they pass the nymph state in cavities in the earth, for about three weeks.
Other genera are elophorus and sphceridium; the latter is terrestrial. 6. The lamellicornes are the last family of the pentamera, including numerous genera, among which are some of the most brilliant and the largest of the order; those that feed on vegetable substances are beautifully colored, while dark tints prevail among those which devour decaying animal matters. The antennae are deeply inserted under the side of the head, short, ending in a knob, composed of plates or laminse. An idea of the form of the larvae, which are often very destructive to vegetation, may be formed from the well known white worm, the larva of the melolontha. In this family is included the genus scarabmus of Linnaeus, proper to warm climates, particularly Africa; they live in ordure of all kinds; the eutachus sacer, an object of religious veneration among the ancient Egyptians, and often represented on their monuments, and found in the sarcophagi, belongs to this genus. Other genera are copris, geotrupes, trox, melolontha, cetonia, and lucanus (stag beetle). While many of the melolonthians are destructive, the geotrupidae and scarabmidm are useful in removing carrion and filth. - The heteromera, the second section of the order, are all vegetable feeders; many of them avoid the light.
It includes: 7. The family melasoma, of black or ash-colored species, for the most part apterous, with the elytra as it were soldered together; some of them have a salivary apparatus; they dwell on the ground, under stones, and in dark situations in houses, quitting their retreats at night; they are slow in their movements. Among the genera are pimelia, blaps, and tenebrio (meal worms). They and their larvae are useful scavengers.
8. The taxicornes have no corneous tooth on the inner side of the jaws; all are winged, and the legs are not adapted for running; in the males the head is sometimes furnished with horns. Most live on tree fungi or under the bark, or under stones on the ground. Some of the genera are diaperis, phaleria, and ele-dona. These fungus-eaters are useful to man.
9. The stenelytra differ from the preceding chiefly in the antennae; they are very active, concealing themselves under the bark or among the leaves and flowers of trees; some live in fungi, others in old wood. To this belong the genera helops, cistela, dircaea, cedemera, and others serviceable to man. 10. The trache-lides live on plants, of which they devour the leaves and suck the juices. Here belong the genera lagria, pyrochroa, mordella, notoxus, horia, meloe, cantharis, etc.; the C. xesica-toria, or Spanish fly, is well known in medicine for its blistering properties. - The third section, the tetramera, are vegetable feeders. It includes: 11. The rhynchophora, a large and richly ornamented family, living very often in the interior of fruit and seeds, and very destructive to the products of the farm and the orchard; it is easily recognized by its projecting muzzle. Among the genera are bruchus, whose larvae are very destructive; attelabus; brentus; curculio, the greatest pest of the horticulturist; calandra, one of whose species, the weevil, destroys immense quantities of grain; the larvae of the C. palmarum are considered a great dainty by the West Indian blacks. 12. The xylophagi, in the larva state, destroy or render useless great numbers of forest trees by the channels which they gnaw in various directions.
Among the most destructive is the genus scolytus; other genera are bostri-chus and trogosita. 13. The platysoma are found beneath the bark of trees. The principal genus is cucujus. 14. The longicornes have filiform and very long antennae; their larvae live in the interior or beneath the bark of trees, where they are very destructive. Some of the species are among the largest of the order. Among the genera are parandra, cerambyx, cal-lidium, lamia, saperda, and leptura. 15. The eupoda derive their name from the large size of the posterior thighs in many species; they are all winged, and occur on the stems and leaves of plants, especially the liliaceae. Among the genera are sagra, crioceris, and donacia. 16. The cyclica are small, slow in their movements, but often brilliantly colored; the females are very prolific. Here are placed the genera hispa, cassida, cryptocephalus, chrysomela; eumolpus, one species of which, E. vitis, in its larva state, commits great ravages in wine countries; galeruca and altica, possessed of great jumping powers; the latter is often very destructive to turnip crops. 17. The clavipalpi are all gnawers, and may be distinguished by their antennae ending in a knob, and by an internal tooth to the jaws; the body is usually rounded.
Some of the genera are erotylw, triplax, agathidium, and phalacrus. - The last section, the trimera, have the antennae ending in a compressed club formed by the last 3 of the 11 joints; it contains: 18. Thefungicolce, living chielly in fungi and dead wood. The principal genus is eumorphw. 19. The aphidi-phagl are best represented by the genus cocci-nella, or lady-bird; these pretty little beetles, more especially in the larva state, live almost entirely on aphides, or plant-lice, and in this way are of immense service. 20. The psela-phii have short truncated elytra; the species are generally very small, and live on the ground in moist places, and under stones and moss. The types of this, the last family, are the genera pselaphus and claviger. - The cole-optera are exceedingly numerous in species. It is by the occurrence of elytra that this order may be at once recognized; these organs are highly ornamented, and they serve not only to protect the membranous wings, but to shield the body in the dark and dangerous places in which beetles delight to go; and by their expanded surfaces they assist the heavy species in their flight, acting both as a sail and a parachute.