424 



INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



valleys where damage to fruit trees has been done was thought to be 

 limited to Alameda, San Benito, Santa Cruz, Monterey and San Mateo 

 counties and the Santa Clara Valley. During the past two years it 

 has also been discovered in the vicinity of Banning, Riverside County, 

 and in the Upper Ojai Valley, Ventura County. 



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 infested trees. Though principally 

 a peach tree borer, it works almost equally as destructively upon 

 almonds, apricots, prunes, cherries, plums and western chokeeherry 

 (Cerasus demissa). Apple stock is attacked to some degree also. 



s« 



Fig. 432. — Asphaltum around the base of a peach tree to 

 prevent the entrance of the young larva? of the California 

 peach borer. (After Morris, Cal. Agrcl. Exp. Sta. ) 



Control. — Trees budded or grafted upon stocks of any of the host 

 plants are most likely to become infested, while it has been found that 

 the borer will not injure trees grafted upon the Myrobalan plum 

 (Prunus cerasifera). The use of this stock is becoming a sure means 

 of controlling the pest in the future. 



Protective washes of lime-crude oil mixture, lime-sulphur-salt mix- 

 ture, or lime, coal tar, and whale-oil soap are recommended by Dudley 

 Moulton as sprays to be applied before the middle of June. Digging 

 out the worms or killing them with a crooked wire should be practiced 

 in the fall, winter and spring months. 



Earl Morris, 298 Horticultural Commissioner of Santa Clara County, 

 has invented a method of control that appears to be better than any- 

 thing else yet tried. His method consists in applying grades "C" and 

 "D" of hard asphaltum. This is done early in the spring to infested 

 trees, and a heavy coating prevents both the issuance and entrance of 

 from ninety-five to ninety-eight per cent of the insects. The material, 

 boiling hot. is applied from five to six inches below and above the 

 surface of the soil with a brush. Two coatings are recommended. This 

 method should follow fall and spring digging for the borers. 



s Bul. No. 228, Cal. Agrcl. Exp. Sta., pp. 372-374, 1912. 



