170 



INSECTS INJURIOUS TO THE PLUM. 



green, with two dull-white lines down the front, roughened 

 with a number of small green and greenish-white tubercles, 

 and tipped with two of a green color. The bodj above is. 

 a rich dark green, with patches and streaks of creamy white ; 

 the second segment is smaller than the head, and its surface 

 covered with many whitish tubercles; the third, dull whitish 

 green, raised considerably above the second, with a flat ridge, 

 having a long, brownish horn on each side, which is thickly 

 covered with very short spines. The fourth segment is similar 

 in size to the third, with the same sort of ridge above, and a 

 small tubercle on each side, tipped with a cluster of short, 

 whitish spines. On each segment behind these there are two 

 tubercles emitting clusters of whitish spines, those on the sixth 

 and twelfth being much larger than the others, while on each 

 segment behind the fourth, except the ninth, there are sev- 

 eral smaller tubercles of a blue color. There are two large 

 patches of white on the upper part of the body, and a band 

 of the same color along each side. 



Wiien about to change to a chrysalis, the caterpillar suspends 

 itself, head downwards, and, shedding its skin, appears as at 6, 

 Fig. 180, and in about ten or twelve days the butterfly escapes. 

 There are two broods of this insect during the year. The 

 larvse from the eggs deposited by the second brood of butter- 

 flies hibernate when less than half grown, and complete their 

 growth the following spring. They construct from part of 



the leaf a curious little case, 

 ^^^- ^^^ • shown at c, in Fig. 180, which, 



being firmly fastened to the 

 branch by silken threads, 

 serves during the winter 

 months as a shelter and a 

 hiding-place. There are sev- 

 eral parasites which reduce 

 the numbers of this insect; 

 one is a tiny, four-winged fly, which infests the eggs {Tri- 

 chogramma minuta Riley Fig. 181, where a represents the fly; 



