194 



THE MONTHLY BULLETIN. 



the growing inner l);irk, moving 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 especially true on 

 the silver prune. The frass and exuding gum are forced out of exit 

 holes through the sides of the trees, thus greatly facilitating the location 

 of the burrows. The larvre remain in the burrows during the winter 

 montlis and continue fairly active. About January and February they 

 begin to transform into pupa?. These remain in the old burrows for 



Fig. 180. — The California peacli borer ( Sanninoidea opalescens Edw. ). a, lai-va ; &, 

 cocoon and pupal skin ; c, pupa ; c', abdominal segments of same ; c", caudal end of 

 same; d, adult female; e, adult male. Much enlarged. (U. S. Dept. AgTcl.) 



about one and one half months, when the adults emerge in the spring 

 and mate to begin egg laying. There is but one generation of over- 

 lapping broods each j^ear. 



Distribution. — At the present time the peach borer as a pest is 

 confined to the Santa Clara Valley, and to Alameda and San Mateo 

 counties. 



Food Plants. — This insect is limited, as a pest, to a very small area 

 of the State and is much dreaded because of the character of its 

 work and the great damage it does to the trees it infests. Though 

 principally a peach tree borer it works almost equally as destructively 



