Note 104 — Chapter III · THE VITICULTURE OF NEW YORK

Grape berry moth (Polychrosis viteana Clem.).—The young caterpillars feed within the grapes finally causing them to turn dark colored and to wither. This injury is sometimes mistaken for the black-rot. After devouring the soft parts of one grape the caterpillar goes to another, fastening the two together by a silken thread. This may be continued until several in a bunch have been destroyed by one caterpillar. The young caterpillars are very light green in color with a brown head. When full grown they measure about one-fourth of an inch in length and are dark olive green in color tinged slightly with red. The cocoon is formed on a leaf and is partially composed of two small pieces cut out of the leaf. The adults of the spring brood emerge in from twelve to fourteen days. The fore-wings have a bluish tinge and are marked with brown, while the posterior wings are dull brown. The moths are small measuring nearly half an inch from tip to tip when the wings are spread. The eggs are probably laid late in June or early in July. There are two broods annually in this State. As the caterpillars spend most of their lives within the grape berries, spraying does not entirely control the pest. Yet the arsenicals applied for the grape-vine fidia will help much in keeping it in check. Picking and destroying the infested fruit and the leaves containing the cocoons helps much.