360 Report op the Department of Entomology. 



Then agitate the mixture violently for from three to five minutes 

 by pumping into itself under high pressure until a creamy mass is 

 formed, from which the oil does not separate. Fruit-growers are 

 advised not to employ an emulsion which shows a separation of the 

 oil as application of such preparations may cause injuries to the 

 trees. This is used with success by some growers for summer spray- 

 ing against the nymphs at a dilution of one gallon of the emulsion 

 to eight gallons of water. 



Formula 4. Miscible Oils. 



These are proprietary oil emulsions and have been used with very 

 satisfactory results for spraying during March to destroy the hiber- 

 nating flies. One gallon of the miscible oil is usually employed 

 with fifteen gallons of water. They are rather dangerous sprays and 

 should be used only in the spring as buds are swelling and never 

 after buds once begin to show green at the tips. 



FAILURES TO CONTROL PSYLLAt 



Most growers meet with little success in their efforts to protect 

 pear orchards from the psylla. The causes for failures are not 

 always apparent. The most conspicuous weakness in present 

 methods of combating the insect is the lack of a definite system of 

 treatment because of the belief that the pest is periodical in its 

 attacks — a fallacy as shown by the experiences in many of the best 

 and well-known pear orchards in this State. The average grower 

 is not accustomed to spray annually and consequently there is a 

 period of one or more years when breeding of the pest is uninterrupted, 

 which permits the psylla to develop to destructive numbers. More- 

 over orchardists are not familiar with the life history and habits 

 of the insect, and spraying operations conducted without any knowl- 

 edge of an insect's activities are not as a rule calculated to give 

 uniformly efficient results. It is a common experience that the 

 presence of the psylla in numbers capable of causing much harm 

 is usually not apprehended until the appearance of honeydew in 

 more or less conspicuous quantities. These conditions are most 

 unfavorable for effective spraying. 



