Page:EB1911 - Volume 13.djvu/274

a family of predaceous bugs that attack other insects and suck their juices; the beak is short, and carried under the head in a hook-like curve, not—as in the preceding families—lying close against the breast. The Cimicidae have the feet three-segmented and the forewings greatly reduced; most of the species are parasites on birds and bats, but one—Cimex lectidarius (figs. 3, 8)—is the well-known “bed-bug” which abounds in unclean dwellings and sucks human blood (see Bug). The Anthocoridae are nearly related to the Cimicidae, but the wings are usually well developed and the forewing possesses cuneus and embolium as well as corium and clavus. The Capsidae are a large family of rather soft-skinned bugs mostly elongate in form with the two basal segments of the feelers stouter than the two terminal. The forewing in this family has a cuneus (fig. 9 cu), but not an embolium. These insects are often found in large numbers on plants whose juices they suck.

Cryptocerata.—In this tribe are included five or six families of aquatic Heteroptera which spend the greater part of their lives submerged, diving and swimming through the water. The feelers are very small and are often hidden in cavities beneath the head. The Naucoridae and Belostomatidae are flattened insects, with four-segmented feelers and fore-legs inserted at the front of the prosternum. Two species of the former family inhabit our islands, but the Belostomatidae are found only in the warmer regions of the globe; some of them, attaining a length of 4 to 5 in., are giants among insects. The Nepidae (fig. 6) or water-scorpions (q.v.)—two British species—are distinguished by their three-segmented feelers, their raptorial fore-legs (in which the shin and foot, fused together, work like a sharp knife-blade on the grooved thigh), and their elongate tail-processes formed of the abdominal pleura and used for respiration. The Notonectidae, or “water-boatmen” (q.v.) have convex ovoid bodies admirably adapted for aquatic life. By means of the oar-like hind-legs they swim actively through the water with the ventral surface upwards; the fore-legs are inserted at the hinder edge of the prosternum. The Corixidae are small flattened water-bugs, with very short unjointed beak, the labrum being enclosed within the second maxillae, and the foot in the fore and intermediate leg having but a single segment. The hinder abdominal segments in the male show a curious asymmetrical arrangement, the sixth segment bearing on its upper side a small stalked plate (strigil) of unknown function, furnished with rows of teeth. On account of the reduction and modification of the jaws in the Corixidae, C. Börner has lately suggested that they should form a special sub-order of Hemiptera—the Sandaliorrhyncha.

From Mariatt, Bull. 14 (N. S.), Div. Ent. U.S. Dept. Agr.

Fig. 10.—a, Nymph (4th stage) of Cicad, magnified; c, d, inner and outer faces of front leg, magnified—; b, teeth on thigh, more highly magnified.

Homoptera

This sub-order includes the cicads, lantern-flies, frog-hoppers, aphids and scale-insects. The face has such a marked backward slope (see fig. 1) as to bring the beak into close contact with the haunches of the fore-legs. The feelers have one or more thickened basal segments, while the remaining segments are slender and thread-like. The fore-wings are sometimes membranous like the hind-wings, usually they are firmer in texture, but they never show the distinct areas that characterize the wings of Heteroptera. When at rest the wings of Homoptera slope roofwise across the back of the insect. In their life-history the Homoptera are more specialized than the Heteroptera; the young insect often differs markedly from its parent and does not live in the same situations; while in some families there is a passive stage before the last moult.

After Weed, Riley and Howard, Insect Life, vol iii.

Fig. 11.—Cabbage Aphid (Aphisbrassicae). a, Male; c, female (wingless). Magnified. b and d, Head and feelers of male and female, more highly magnified.

After Howard, Year Book U.S. Dept. Agr., 1894.

Fig. 12.—Apple Scale Insect (Mytilaspis pomorum). a, Male; e, female; c, larva magnified—; b, foot of male; d, feeler of larva, more highly magnified.

The Cicadidae are for the most part large insects with ample wings; they are distinguished from other Homoptera by the front thighs being thickened and toothed beneath. The broad head carries, in addition to the prominent compound eyes, three simple eyes (ocelli) on the crown, while the feeler consists of a stout basal segment, followed by five slender segments. The female, by means of her serrated ovipositor, lays her eggs in slits cut in the twigs of plants. The young have simple feelers and stout fore-legs (fig. 10) adapted for digging; they live underground and feed on the roots of plants. In the case of a North American species it is known that this larval life lasts for seventeen years. The “song” of the male cicads is notorious and the structures by which it is produced have already been described (see also Cicada). There are about 900 known species, but the family is mostly confined to warm countries; only a single cicad is found in England, and that is restricted to the south.

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After Howard, Year Book U.S. Dept. Agr., 1894.

Fig. 13.—Apple Scale Insect (Mytilaspis pomorum). a, Scale from beneath showing female and eggs; b, from above, magnified—; c and e, female and male scales on twigs, natural size; d, male scale magnified.

From Osborn (after Denny), Bull. 5 (N.S.), Div. Ent. U.S. Dept. Agr.

Fig. 14.—Louse (Pediculus vestimenti). Magnified.

The Fulgoridae and Membracidae are two allied families most of whose members are also natives of hot regions. The Fulgoridae