But it is kindly ordained that these visitations shall only occasionally take place, and even when they do, terrible as is the infliction, a benefit in reality outweighing the injury often succeeds; for the land in these countries is often made almost barren by the quantities of tangled roots and stubble on the surface of the earth, which by the destructive powers of these insects is completely removed, and their manure left in its place, so that the fertility of the ground is much increased (often tenfold) after their visits.
The thousands of species of insects which exist, render it impossible in a work like this, even to name them, but under the separate orders will be given a slight outline of the more important.
FIG. 22.—THE STAG BEETLE (Lucanus cervus).
Insects are divided, according to the character of their wings, into nine orders.
1. Coleoptera (Black-winged).
The Coleoptera are those insects generally denominated Beetles, they have four wings, the two outer of which are not used to fly with, but as cases to cover and protect the other two; they are called "elytra," are horny and firm in texture, and in some cases, as the Diamond Beetle and Musk Beetle, beautifully ornamented; the under pair of wings fold transversely so as to pack up under the outer ones, which are shorter. All Beetles live but one season, both sexes die before winter, leaving nothing but their eggs to continue the species, the larvæ which come from these are very destructive, eating most voraciously; for the most part, Beetles feed on decaying substances such as dung, &c., and are therefore useful creatures; there are between 40,000 and 50,000 species of them. Beetles have been called the scavengers of nature, and truly they are so, for they (with other insects) clear off all dead matter, whether animal or vegetable; the Geotrupes stercorarius, and others, dig holes in the ground and bury the excrement which is deposited on the surface, thus doing a great service to vegetation, taking it down to nourish the roots of the grass and other plants instead of allowing it to harden and decompose on the surface. All dead animals are at once attacked and devoured by insects, and the Beetles play their full share in this necessary operation.
There are certain Beetles, called Burying Beetles (Necrophorus vespillo), which remove the earth from under the dead bodies of small animals, such as birds or mice, till they are beneath the level of the ground, when they cover them up and deposit their eggs in them; these bodies form stores of food for the future larvæ.
The Stag Beetle (Lucanus cervus, fig. 22), the Dor Beetle (Geotrupes stercorarius), the Cockchaffer (Melolontha vulgaris), the Musk Beetle (Cerambyx moschatus, fig. 16), and the Lady-bird (Coccinella), are well-known members of this order.
2. Orthoptera (Straight-winged).