800 Pomona College Journal op Entomology 



Fumigation — A very peculiar characterrstic of this scale is its resistance 

 to hydrocyanic gas fumigation quite soon after it has been hatched out, while 

 it is still in the early greenish or yellowish stage, in fact, and should be easy 

 to kill. Last year the latest date on which a good killing was obtained was 

 October 9, but this year no useful work has been done on it since September 13. 

 On the other hand, if fumigated before the young has all been born (August 

 21 the last two years) perfect results cannot be looked for, as though all the 

 young scales, including those still under the old shells, can be killed, the 

 mothers are not killed, and continue to bring forth young. Practically, how- 

 ever, the number of unborn young still remaining after, say, July 15, would 

 probably not be large enough to be serious. This would give us a fumigating 

 season lasting from July 15 to early in September. This would be too early, 

 most years, to get a good killing with the black scale, while fumigating as 

 early as July would be liable to drop fruit unless very cool nights happened to 

 be available. With regard to the dosage, very good results have been ob- 

 tained, between the dates mentioned, with doses as low as the half schedule, 

 while after the end of August very poor results have been obtained with dose 

 as high as one ounce of cyanide to the hundred cubic feet. I hope to be able 

 to give more definite results before next fumigating season. I do not think 

 there is much use in fumigating for "longnlus" from now on until July 15. 



Spraying — ^We have tried various sprays on this scale, and have killed a 

 fair proportion, probably, of those reached by the spray, but in no case was a 

 result obtained that could be looked upon as satisfactory. 



