Page:The New International Encyclopædia 1st ed. v. 02.djvu/789

BEETLE. climb, swim, and burrow. Most of them are extremely active, and hence have well-developed legs and feet. Tliese are all much alike in the ground-runners and tree-climbers, l)ut variety is found among those of more special haunts and

BACK OF A BEETLE. a. Head: 6, Protliorax; c, Scntelluni of meeo thorax ; </, hind wing; e. Elytra (front wings); f, Spiracles: g. Segments cf abdomen.

habits. Tlius, the jumpers have very long hind legs, with thickened femora; the diggers have thickened fore legs, with claws turned into e.xca- vators : the aquatic beetles have all or a part of their legs disposed as oars, and made broad and flat and bordered with bristles. The parts of the legs vary considerably, and with such regu- larity that the form of the coxa is used as one of the main standards in classifying families, while larger groups — Pentamera, Tetramera, etc. — are based on number and characteristics of joints in the tarsi. "The tarsal joints are hairy beneath, and those of the anterior (and sometimes also the middle) pair of legs of many male beetles are modified to elasp more firmly the female during copulation." The most pe- culiar of these modifications is seen among water beetles (Dysticidfe). The legs of larvie are often reduced to mere rudiments, or are absent.

The Hind Body is made up of the two posterior thoracic segments and the abdomen, and is en- tirely hidden from dorsal view in most beetles by the wing covers, but the parts can be well seen on the ventral surface. To the mesothorax are attached the middle pair of legs and the wing covers, while the metathorax supports the hindmost legs and the membranous flying wings, which, when not in use, are curiously folded out of harm's way under the elytra, which also shield the soft-skinned abdomen. The elytra are not instruments of flight, except that they may be useful as balancers, when held out at right angles. They shut close together ujion the back when at rest, and in some forms are closely united by a suture along the median line ; or, in the case of certain running beetles, where the wings may be greatly aborted or perhaps may even be altogether absent, particularly in the female sex, the elytra may even be wholly grown together into one shield. The elytra may be smooth and plainly colored, or may be highly polished, striated, pitted, and sculptured in a great variety of ways, as usually occurs in the terrestrial families. They may also bear spines, few or many, long and short, tubercles, and other prominences, or be clothed with pubescence or scattei'ed hairs or scales or wa.xy secretions. "The excessive brilliancy and spai'kling colora- tion of the diamond beetle of Brazil ... is due to its being covered with scales ; this . . . is common among the weevils (Curculionidfc) and not rare in a few other families 'of Coleop- tei-a." Beetles exhibit almost every known shade of color (see Plate), and a few are iridescent, with beautiful metallic hues. A little beetle (Coplocjicla anrichalcca), not imcommon on the wild morning-glory (C(mvolvulus) . looks, when alive, like a flattened drop of the finest polished gold. The species of certain families resemble one anotlier in coloration and figuration; the leaf beetles (Chrysonielidae) have, for the most part, brilliant coloration; the ladybirds (Coc- einellidie) have, for prevailing colors, red, yel- low, and black, mostly arranged in round or roundish spots" (Dimmock). As a general rule those whose lives are passed in the open sun- light are more bright in color than those that habitually dwell in cavities, under stones or water, or in the dark.

Habits and Food. Beetles dwell in the great- est variety of situations, and in nearly all parts of the 'orld. A few live in salt water, more in fresh waters, and a limited number breed in hot springs. Under great stones and in caves dwell a good many blind beetles, the degenera- tion of the visual organs in some of which has

rKDEn SIDE op A BEETLE. s 1, Prosterniim ; s 2, Mesosternum ; s 3. Metasternum; f, f, Epimera of mesothorax : 1, 2, 3, 4, 5. 6, Joint.s of abdomen. Joints of hind legs: a. Coxa: b. Trochanter; c. Femur; d. Tibia; e, Tarsus.

proceeded so far as to include even the optic nerves and lobes. Certain other forms are para- sites in other animals or are to be found in the nests of termites and ants; for the very inter- esting facts of this association, see Symbiosis. The food of beetles and their young is as di- verse as tlieir habitats. A vast number of them, such as Hydrophilidse and Chrysomelidte, feed on vegetable matter, both living and dead, above