270 



LEPIDOPTERA. 



foregoing characters. 



Fig. 99. 



It is the Pontia oleracea^ (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 

 Farmer." * 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 week or ten days 

 after they are laid, and the caterpillars produced fi'om them 

 attain their ftill 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 devom- 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 Ponlia okracea belongs to the genus Pieris Schrk. (MoiTis's Catalogue). 

 The P. casta of Kirby, in Faun. Bor., IV. 288, is only a variety of Harris's P. 

 okracea; and Kirby's casta is the cruciferarum of Boisd. Spec. Gen. I. 519. 



JIOBKIS.] 



* Page 402. For a figure of it, see " Lake Superior," by Agassiz and Cabot, 

 pi. 7, fig. 1. 



