Fig. 62.—The female red orange scale insect, Aspidiotus aurantii, very injurious to orange-trees. It has no wings, legs, nor eyes, but remains motionless on a leaf, stem, or fruit, holding fast by its long slender beak, through which it sucks up the plant-sap. The male is winged, and has no mouth-parts, taking no food. (Photo-micrograph by Geo. O. Mitchell.) Fig. 63.—The female rose-scale, Diaspis rosæ, a pest of rose-bushes, without eyes, wings, or legs, but with slender sucking proboscis. The male is winged and without mouth-parts. (Photo-micrograph by Geo. O. Mitchell.)

The Hemiptera are characterized particularly by their highly specialized sucking mouth-parts, no other of the sucking insects having the proboscis composed in the same manner. The palpi of both maxillæ and labium are wholly wanting in Hemiptera and the flexible needle-like maxillæ and mandibles are enclosed in the tubular labium. This order is a large one and includes many well-known injurious species, as the chinch-bug (Blissus leucopterus), which occurs in immense numbers in the grain-fields of the Mississippi valley, sucking the juices from the leaves of corn and wheat, the grape Phylloxera (Phylloxera vastatrix), so destructive to the vines of Europe and California, the scale insects (Coccidæ) (figs. [62] and [63]), the worst insect pests of oranges, the squash-bugs and cabbage-bug and a host of others. Some of the Hemiptera, for example, the lice and bed-bugs, are predaceous, sucking the blood of other animals.

Fig. 64.—A water-strider, Hygrotrechus
sp. (From Jenkins and Kellogg.)

The water-striders (fig. [64]) catch other insects, both those that live in the water and those which fall on to its surface, and holding the prey with their seizing fore legs they pierce its body with their sharp beak and suck its blood. They lay their eggs in the spring glued fast to water-plants. The young water-striders are shorter and stouter in shape than the adults.

Fig. 65.—A water-boatman, Corisa
sp. (From Jenkins and Kellogg.)

The water-boatmen (fig. [65]) and back-swimmers swim and dive about in the water, coming more or less frequently to the surface to get a supply of air. This air they hold under the wings, or on the sides and under part of the body entangled in the fine hairs on the surface. The insects appear to have silvery spots on the body, due to the presence of this air. The "rowing" legs of the water-boatmen (Corisa) are the hindmost pair; in the back-swimmers (Notonecta) they are the middle legs.