26 EffJUEIOUS IKSEOTS 



across its back and secures on the other side, and repeats 

 this operation until a band, or loop, of sufficient strength 

 is formed. On the next day it casts oil the caterpillar 

 skin, and becomes a chrysalis (fig. 19). This is 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 tuber- 

 cle, 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 Roman nose. 

 The insect remains in this stage for ten or twelve days, 

 when the butterfly appears. 



In the last of July and first of August, these insects 

 may be seen in large numbers depositing their eggs for a 

 second brood, which, wintering in the pupa state, pro- 

 Luces the perfect insect (fig. 18, l) the following May. 



This butterfiy varies considerably. There are never, 

 we believe, perfectly white specimens, though often 

 nearly so. Again, some specimens have very faint indi- 

 cations of spots arranged as in P. rapm; but on the 

 under side are found the widest limits of variation, for 

 not only do the tips of the front wings become distinctly 

 greenish, or lemon-yellow, and the veins of that portion 

 bordered with grayish scales, but the hind wings may 

 also have the ground color distinctly greenish, lemon- 

 yellow, or whitish, and the veins display gray scales on 

 each side. 



By taking advantage of the habits of these insects, 

 they might be nearly exterminated. If boards are placed 

 among the infested plants, about two inches above the 

 ground, the caterpillars when about to change will resort 

 to them, and there undergo their metamorphoses. They 

 may then be collected by hand on the under side of the 

 boards, and destroyed. As the butterflies are slow fliers, 

 they may be taken in a net and killed. A short handle, 

 perhaps four feet long, with a wire hoop, and bag-net of 



