INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



423 



are arranged singly or in small groups of from three to fifteen. Each 

 moth lays from two hundred to over four hundred eggs, and it 

 requires from fifteen to thirty clays for them to hatch. The newly 

 hatched larva? immediately seek shelter in cracks or crevices of the bark 

 or beneath the ground and at once begin to enter the trunk of the 

 tree by boring with great rapidity through the bark, or in infested 

 orchards they enter the old 

 burrows. During the sum- 

 mer the young work upon 

 the growing inner bark, 

 burrowing downward or 

 upward at will. The bur- 

 rows are usually made 

 under the surface of the 

 ground, but occasionally 

 they are extended quite far 

 up the trunks. This is 

 espeeiall.v true on the silver 

 prune. The frass and gum 

 are forced out of exit holes 

 through the sides of the 

 trees, thus greatly facili- 

 tating the location of the 

 burrows. The larvae re- 

 main in the burrows during 

 the winter months and con- 

 tinue fairly active. About 

 January and February 

 they begin to transform 

 into pups?. These remain 

 in the old burrows for 

 about one and one h*n]f 

 months, when the adults 

 emerge in the spring and 

 mate to begin egg-laying. 

 There is but one generation 

 a year. 



Nature of Work.— The 



caterpillars usually work 

 around the crown of the 

 tree, just under the bark, 

 near the surface of the 

 ground, though their bur- 

 rows may extend quite far up the trunk. The work after successive 

 seasons usually serves to entirely girdle and kill the tree in time. The 

 exuding gum and rejected frass from the entrance of the burrows are 

 evidences of the presence of the larvae, in addition to the unhealthy 

 appearance of the tree which accompanies the attacks. 



Distribution. — The distribution of the peach borer is wider than 

 was first realized. Adults have often been taken by collectors in the 

 mountains, especially the Sierra Nevadas. but the distribution in the 



Fig. 431. — The California peach borer, fflgeria 



opalescens H. Bdw. Cocoons and pupal skins al 

 top; male and female moths at the bottom. Nat- 

 ural size. (Original) 



