164 INSECTS INJURIOUS TO THE PLUM. 



rapacious appetite, this larva often assumes for a time the 

 peculiar rigid appearance shown in the cut. Though pre- 

 senting a formidable aspect, it is perfectly harmless, and may 



Fig. 171. 



be handled with impunity; it may be found on the trees from 

 the middle of July to the end of August. 



When mature, the caterpillar descends to the ground, and, 

 having buried itself under the surface to the depth of several 

 inches, prepares a convenient chamber, which it lines with a 

 gummy, water-proof cement, and there changes to a chrysalis, 

 as shown in Fig. 172, which is about an inch and a half long, 



of a dark reddish -brown 

 color, with a short, thick, 

 projecting tongue-case. The 

 insect remains in the ground 

 in this condition until the 

 following June ; indeed, oc- 

 casionally specimens have been known to remain in this torpid 

 state until the spring of the second year following. 



The ravages of the plum-tree sphinx are never very ex- 

 tensive, yet it appears at times in some localities in sufficient 

 numbers to cause annoyance. The denuded twigs promptly 

 attract the attention of the vigilant fruit-grower, who will 

 eoon search out and exterminate the destroyer. 



