424 Report of the Department of Entomology of the 



INTRODUCTION. 



Failures to control psylla in pear orchards by summer spraying 

 to destroy the nymphs only, have led the Station to inquire into the 

 susceptibility of the insect to spraying mixtures at other stages of 

 its life. Attention has been given especially to the hibernating adults 

 and to the eggs of this brood, for it has seemed on casual observations 

 that these, under certain conditions, might be quite vulnerable to 

 treatment. This conviction was further strengthened by a study 

 of the literature on the species, which has indicated the possibility 

 of protecting orchards by combating the insects in either of these 

 stages, and has emphasized the desirability of experiments along 

 the proposed lines. 



HISTORICAL SUMMARY OF SPRAYING FOR ADULTS AND 



EGGS. 



In 1896 Dr. J. B. Smith 1 of the New Jersey Station suggested 

 that " the application of whale-oil soap early in the spring, just as 

 the buds begin to swell, will generally kill the insects (hibernating 

 flies), which are then ready to emerge from winter quarters. Good 

 practice is to scrape all the loose bark from the trees during the winter, 

 and burn it; wash at that time with a potash or strong kerosene 

 mixture, and in the spring use the whale-oil soap at the rate of one 

 pound in one gallon of water, being careful to confine the spraying 

 to the trunk and larger branches. If this is thoroughly done, it 

 forms a film over the trunk which no insect will voluntarily pierce. 

 A liberal application of whitewash is also advantageous * * *." 



Prof. M. V. Slingerland 2 in 1899 recommended that " as these 

 hibernating psyllas are the progenitors of all that will appear on the 

 trees during the following season one can readily see how much it 

 means to kill these over-wintering adults before they begin egg laying 

 in the spring. Drenching the bark thoroughly with a strong kerosene 

 emulsion (1 part emulsion to 4 or 5 of water), whale-oil soap (one 

 pound in three to five gallons of water), or kerosene, using about one 

 part of kerosene to nine or ten parts of water, would be a wise 

 investment." 



•Economic Entomology, p. 138. 1896. 

 2 Proc. W. N. Y. Hort. Soc. 44:71. 1899. 



