Page:Popular Science Monthly Volume 42.djvu/659

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AN AGRICULTURAL REVOLUTION.

as large a profit from the agriculture of this great agricultural State as do the farmers themselves."

Fortunately, however, much progress has recently been made in a knowledge of efficient means of preventing this vast drain upon our productive system. By the introduction of a simple mechanical contrivance for the application of insecticides and fungicides, the methods of combating these foes have been revolutionized; and in many localities where the production of special crops had been abandoned new life has been put into their development. This contrivance is commonly called the spraying machine. It consists essentially of a force pump and spray nozzle connected with a reservoir, by means of which certain substances that have a destructive effect upon insect and fungousPSM V42 D659 Codling moth.jpgFig. 1.—Codling Moth: a, injured apple; b, place where egg is laid; e, larva; d, pupa; i, cocoon; g, f, moth; h, head of larva. (After Riley.) life may be rapidly and evenly distributed over the outer surfaces of trees, shrubs, vines, and herbaceous plants.

In America the spraying machine seems to have first come into general use to prevent the injuries of the codling moth or apple worm. This is a very destructive and widely distributed insect, for which there had before been known no remedy that can compare with spraying in cheapness and efficiency. These worms hatch from eggs laid in the calyx ends of the newly formed apples by a small, chocolate-colored moth (represented at f and g, Fig. 1). These eggs are deposited in spring or early summer, from the time the young apples are as large as peas until they attain the size of small hickory nuts. The eggs are placed on the outside of the fruit, and the resulting worms nibble at the skin, finally biting through and eating toward the core. They continue feeding for three or four weeks, when they become three fourths of an inch long, whitish or pinkish-white in color, and of the general form shown in Fig. 1, e. They are now full grown as larvæ, and leave the apples to spin, in some temporary shelter, slight silken cocoons (i), in which they transform to pupæ (d), to change a fortnight later into fall-fledged moths. These moths deposit eggs about midsummer for a second brood of worms.

The earlier preventives of codling-moth injury included such partially effective measures as banding the trees with wisps of