214 INSECTS INJURIOUS TO VEGETATION. 



butterfly, and was first described by me in the year 1829, in the 

 seventh volume of the "New England Farmer."* About the 

 last of May, and the beginning of June, it is seen fluttering 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 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 distin- 

 guished from the ribs of the leaves beneath which they Hve. 

 They do not devour the leaf at its edge, but begin indiscrimi- 

 nately upon any part of its under-side, through which they eat irre- 

 gular 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 foi-m a loop to sustain the forepart 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 its back and secures on the other 

 side, and repeats this operation till the united threads have formed 

 a band or loop of sufficient strength. On the next day it casts off 

 the caterpillar skin, and becomes a chrysalis. This is sometimes 

 of a pale green, and sometimes of a white color, regularly and 

 finely dotted with black ; the sides of the body are angular, the 

 head is surmounted by a conical tubercle, and over the forepart 

 of the body, corresponding to the thorax of the included butterfly, 

 is a thin projection, having in profile some resemblance to a Ro- 

 man nose. The chrysalis state lasts eleven days, at the expira- 

 tion of which the insect comes forth a butterfly. The wings are 

 white, but dusky next to the body ; the tips of the upper ones are 

 yellowish beneath, with dusky veins ; the under-side of the hinder 

 wings is straw-colored, with broad dusky veins, and the angles 



* Pajre 402. 



