. A treatise on some of the insects injurious to vegetation . Insect pests. 270 LEPIDOPTEEA. foregoing characters. It is the Pontia oleracea6 (Fig. 99), potherb Pontia, or white butterfly, and was first de- scribed by me in the year 1829, in the seventh vol- ume of the " New England ;* About the last of May, and the beginning of June, it is seen flutter- ing over cabbage, radish, and turnip beds, and patches of mustard, for the purpose of depositing its eggs. These are fastened to the under sides of the leaves, and but seldom more than three or four are left upon one leaf. The
. A treatise on some of the insects injurious to vegetation . Insect pests. 270 LEPIDOPTEEA. foregoing characters. It is the Pontia oleracea6 (Fig. 99), potherb Pontia, or white butterfly, and was first de- scribed by me in the year 1829, in the seventh vol- ume of the " New England ;* About the last of May, and the beginning of June, it is seen flutter- ing over cabbage, radish, and turnip beds, and patches of mustard, for the purpose of depositing its eggs. These are fastened to the under sides of the leaves, and but seldom more than three or four are left upon one leaf. The eggs are yellowish, nearly pear- shaped, longitudinally ribbed, and are one fifteenth of an inch in length. They are hatched in a ten days after they are laid, and the caterpillars produced from them attain their full size when three weeks old, and then measure about one inch and a half in length. Being of a pale green color, they are not readily distinguished from the ribs of the leaves beneath which they live. They do not devour the leaf at its edge, but begin indiscriminately upon any part of its under side, through which they eat irregular holes. When they have completed the feeding stage, they quit the plants, and retire beneath palings, or the edges of stones, or into the interstices of walls, where they spin a little tuft of silk, entangle the hooks of their hindmost feet in it, and then proceed to form a loop to sustain the fore part of the body in a horizontal or vertical position. Bending its head on one side, the caterpillar fastens to the surface, beneath the middle of its body, a silken thread, which it carries across [6 Pontia oleracea belongs to the genus Pieris Schrk. (Morris's Catalogue). The P. casta of Kirby, in Faun. Bpr., IV. 288, is only a variety of Harris's P. oleracea; and Kirby's casta is the cruciferarum of Boisd. Spec. Gen., I. 619. — Mokkis.] * Page 402. For a figure of it, see " Lake Superior," by Agassiz and Cabot, pi. 7, fig.
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