The Hemiptera display a greater diversity of form than any other order of insects, and vary in size from almost microscopic scales to fat cicadas and "giant" water bugs. "Some pass their lives in the upper parts of trees, others chiefly on the lower limbs; still others prefer the protection of roots, stones or rubbish on the ground; a large number of species select a home beneath the surface of the earth, often in the holes of ants or other insects; a conspicuous assemblage of dull-colored forms occurs only in the crevices or under the bark of trees and shrubs; while a host of others skim over the surface of placid waters, and a few are found remote from land upon the rarely disturbed waves of the tropical and subtropical oceans.... While the greater number derive their food either from the sap of vegetables, or the blood of fishes, animals and man, there are others which are satisfied with the strong fluid that accumulates beneath damp, decaying bark of trees, or still others which enjoy the juices of fungi or ferns.... Those which creep about in search of living prey are often furnished with curved or hooked forelegs, suitable for seizing and holding creatures when in motion, such as caterpillars and other larvæ."
The Homoptera include the immense and destructive family Coccidæ, the bark lice, scale insects, and mealy bugs, among which, however, are the useful producers of lacs and such dyes as cochineal. Related to them are the Aleyrodidæ, the destructive "white flies," and the Aphidæ, almost infinite in number and in harmfulness to fruit trees and cultivated plants; also the queerly shaped leaf hoppers and similar minute, plant-sucking forms.
It is one of the curiosities of zoölogy that associated with these minutiæ we find a family of bugs of large size—the cicadas, whose loud "singing" by the male in autumn gives them the name "locust," and often becomes annoying when one wants to sleep where trees are near by. The noise is made by vibrating membranes stretched over a pair of sound chambers, situated, one on each side, near the base of the abdomen. The cicada lays its eggs in slits cut in the bark. The newly hatched young drops to the ground and, burrowing into it, feeds by sucking the juices of roots. The time spent in the ground varies according to the species in various parts of the world. In the case of our "periodical" cicada it lasts about seventeen years, whence we call that species "seventeen-year locust," and know it, when a great swarm comes out of the ground and ascends the trees, by the humming of the crowd which sounds like the vibration of telegraph wires in the poles.
| SEVENTEEN-YEAR LOCUSTS |
| 1-4, pupæ, increasing in age; 5-15, the locust imago struggling out of the pupa; 16, 17, 18, the imago stretching its wings; 19, empty pupacase; 20, 21, perfect locust. (Smithsonian Institution.) |
The Heteroptera, or proper "bugs," are a much larger assemblage, a few kinds of which have attracted popular notice. The long catalogue begins with the small "water boatmen" that live an active predatory life on the bottom of streams and ponds. Other common aquatic families are the Notonectidæ, that swim on their backs, the Nepidæ, or "water scorpions," one of whose genera is that of the slender, long-legged "skaters" that glide so swiftly across the glassy surface of still waters. Then there are the great water bugs (Belostoma), which all over the world are the tigers of quiet rivers and ponds, pouncing from their concealed lairs on even minnows, small frogs, and anything else they can catch and kill. These great brown bandits are sometimes two inches long. Some of the tropical species are strange in form and have extraordinary habits in caring for eggs and young.
Leaving the aquatic group, we come to certain troublesome plant-sucking bugs, and to the bedbug, which claims the longest lineage of any known insect, for the remains of perfectly recognizable ancestors are found in Ordovician rocks dating from early in the Paleozoic time. Skipping the lace bugs, red bugs, or "cotton stainers," and others, we come to a series of families that are among the worst pests of the farmer and gardener, the chinch bug, squash bug, cabbage bug and many others, the aggregate effect of whose ravages causes a loss of millions of dollars' worth of crops every year, not only in this country, but everywhere that grain, vegetables, and fruit are cultivated; and in most cases it is not the native but introduced species that does the most damage.
GILDED BUTTERFLIES AND DUSTY MOTHS
The butterflies and moths, whose beauty attracts more collectors than any other group of insects, constitute the order Lepidoptera, the meaning of which term is "scaly winged," in reference to the fact that the hairs that clothe and ornament the wings are scalelike. Butterflies have club-shaped antennæ, and belong to the division Rhopalocera. Moths are Heterocera. Some of the moths, especially the males, have feathered antennæ, some threadlike, while a few tropical ones have "club" antennæ, so that this distinction is not perfect. The pupæ of butterflies are not protected by cocoons, as are those of most moths, and are usually called "chrysalides" (singular, "chrysalis"). Butterflies in general only fly during the daylight, when few moths are stirring, and usually hold their wings erect when at rest, while moths hold them flat or folded against the body.