of the United States were in the habit of destroying the redheaded woodpecker, the great enemy of these insects, because he occasionally spoilt an apple.[G] The same delightful writer and true naturalist, speaking of the labours of the ivory-billed woodpecker, says, "Would it be believed that the larvæ of an insect or fly, no larger than a grain of rice, should silently, and in one season, destroy some thousand acres of pine-trees, many of them from two to three feet in diameter, and a hundred and fifty feet high? In some places the whole woods, as far as you can see around you, are dead, stripped of the bark, their wintry-looking arms and bare trunks bleaching in the sun, and tumbling in ruins before every blast."[H] The subterraneous larva of some species of beetle has often caused a complete failure of the seed-corn, as in the district of Halle in 1812.[I] The corn-weevil, which extracts the flour from grain, leaving the husk behind, will destroy the contents of the largest storehouses in a very short period. The wire-worm and the turnip-fly are dreaded by every farmer. The ravages of the locust are too well known not to be at once recollected as an example of the formidable collective power of the insect race. The white ants of tropical countries sweep away whole villages with as much certainty as a fire or an inundation; and ships even have been destroyed by these indefatigable republics. Our own docks and embankments have been threatened by such minute ravagers. The enormous injuries which insects cause to man may thus be held as one reason for ceasing to consider the study of them as an insignificant pursuit; for a knowledge of their structure, their food, their enemies, and their general habits, may lead, as it often has led, to the means of guarding against their injuries. At the same time we derive from them both direct and indirect benefits. The honey of the bee, the dye of the cochineal, and the web of the silk-worm, the advantages of which are obvious, may well be balanced against the destructive propensities of insects which are offensive to man. But a philosophical study of natural history will teach us that the direct benefits which insects confer upon us are even less important than their general uses in maintaining the economy of the world. The mischiefs which result to us from the rapid increase and the activity of insects are merely results of the very principle by which they confer upon us numberless indirect advantages. Forests are swept away by minute beetles; but the same agencies relieve us from that extreme abundance of vegetable matter which would render the earth uninhabitable were this excess not periodically destroyed. In hot countries the great business of removing corrupt animal matter, which the vulture and hyæna imperfectly perform, is effected with certainty and speed by the myriads of insects that spring from the eggs deposited in every carcase by some fly seeking therein the means of life for her progeny.