The cabbage leaf miner is not a native of this country, but was imported from Europe.

The perfect moth, Fig. 25, f, with the wings expanded (h, with the wings closed, g, a dark variety), measures three-quarters of an inch. The fore wings are ashy gray, and on the hinder margin is a white or yellowish white stripe having three points extending into the gray, thus forming, when the wings are closed, three diamond-shaped white spots. Generally there is a dark brown stripe between the white and the gray. There are also black dots scattered about on the anterior part of these wings.

The hind wings are leaden brown, and the under side of all the wings is leaden brown, glossy, and without any dots.

The antennae are whitish with dark rings, and the abdomen white. There are two broods of this insect in this region, the moths of the first appearing in May, and those of the second in August. They hibernate in the pupa stage.

The caterpillars, Fig. 25, a (b, the top and c, the side of a segment), appear in June or July and September; they are small and cylindrical, tapering at both ends, pale green, and about one-fourth of an inch long. The head has a yellowish tinge, and there are several dark stiff hairs scattered over the body.

When ready to transform, this caterpillar spins a delicate gauze-like cocoon, Fig. 25, e, made of white, silken threads, on the under side of a cabbage leaf. The pupa, Fig. 25, d, and i, the end of a pupa, is commonly white, sometimes shaded with reddish brown, and can be distinctly seen through the silken case.

The first brood is more injurious than the second, as it feeds on the young cabbage leaves before the head is formed, and this must surely stunt the growth and make weak, sickly plants; while the second brood feeds only on the outside leaves. The caterpillars are very active, wriggling violently when disturbed, and falling by a white silken thread.

Hot dry weather is favorable to them and enables them to multiply rapidly. Advantage has been taken of this fact, and spraying the plants thoroughly with water is strongly recommended. Prof. Riley states that the insects are very readily destroyed by pyrethrum. There are two species of spiders and a species of ichneumon fly that destroy them.