CANKER WORM, Anisopterys, a genus of destructive insects of the order lepidoptera and family geometridre. The female moths, from the eggs of which this worm comes, are wingless. In the spring they creep up the trunks of trees, on which they deposit their eggs. These soon produce the worms, which feed upon young leaves of fruit trees and of nearly all cultivated trees. After about four weeks of feeding they creep down, or let themselves down by a web, and burrow in the ground, where they change to chrysalis, and remain until the following spring. Like other geometridue, the worm has six legs forward and four stout prop legs behind. In consequence of their singular mode of locomotion they are often called measuring, or inch or span, or loop worms or geometers. As the female moth cannot fly, trees may be protected from this worm, by surrounding their trunks with a hollow vessel filled with oil or thin tar, which prevents the ascent of the egg-laying moth; but in recent years the sparrows introduced from England have entirely subdued this worm in many districts that had been completely denuded of leaves almost every summer. This remedy, however, is worse than the
disease. The English sparrow is not, in general, an insect-eating, but is a grain-eating bird; it is very pugnacious, and as prolific as the rabbit; it has driven away the native birds wherever it has gained a footing, and as there are many other insect leaf-eaters which it will not touch, and which no other birds are left to destroy, the trees are in nearly as great danger as before, while the grain-fields of farmers are beginning to suffer severely from the ravages of the sparrows.