286 FRUIT INSECTS 



about five days, and the young larvse soon excavate small cavi- 

 ties in the bark at the base of the new growth in which to pass 

 the winter. 



Treatment. 



Extensive experiments in California have shown that the 

 peach twig-borer may be satisfactorily controlled by thorough 

 and timely spraying with the lime-sulfur wash. The applica- 

 tion should be made just after the buds begin to swell and may 

 be continued until the first blossoms appear. This is the period 

 at which the young larvae are leaving their winter quarters 

 and are most easily reached by the spray. Kerosene or distil- 

 late emulsion may be used at this time, but is somewhat less 

 effective and is more likely to cause injury. Winter applica- 

 tions of either the emulsions or the lime-sulfur wash are of little 

 value in the control of this insect, because at that time the larvae 

 are out of harm's way in their hibernating burrows in the bark. 

 It was formerly supposed that the oil would be absorbed by the 

 frass, penetrate the burrow and kill the larva, but later work 

 has shown that it penetrates very slowly if at all, and the practice 

 is now generally discarded. In case the early application of the 

 lime-sulfur wash has been omitted it will pay to spray the 

 trunks and larger branches with kerosene or distillate emulsion 

 in late spring to kill the first-brood pupae in their flimsy cocoons 

 in the curls of bark. This treatment cannot be relied upon to 

 control the pest, but may be used to supplement the use of the 

 lime-sulfur wash when for any reason it may seem to have been 

 ineffective. 



References 



U. S. Dept. Agr. Farm. Bull. 80. 1898. 

 Cal. Agr. Exp. Sta. Bull. 144. 1902. 



Cenopis diluticostaria Waslingham sometimes causes an injury 

 to peaches very similar to the work of the peach twig-borer. 

 17th Rept. N. Y. State Ent., p. 736. 1901. 



