THE MONTHLY BULLETIN. 387 



citrus trees in Marysville, which resulted in finding 61 separate infesta- 

 tions, 37 rated as light, 7 medium, and 17 heavy. 



AVhile the pest does not seem to increase with great rapidity, and 

 while there seems little chance of its reaching the citrus sections from a 

 section which is shipping neither fruit nor trees, the present State 

 Commissioner, A. J. Cook, decided that since eradication was impossible, 

 something should be done to keep it under control, and the writer was 

 instructed to proceed to bring about such control in the best way pos- 

 sible. The two methods by which this might be done that naturally sug- 

 gested themselves were fumigation and spraying. Either operation in 

 city lots, where trees are crowded against buildings and surrounded by 

 flower beds, is anything but easily executed. Taking all things into 

 consideration it was finally decided to attempt a campaign of spraying 

 as the easiest solution of the problem, providing that some spray could 

 be found that would be efi:'ective. E. W. Berger and W. W. Yothers 

 had shown that under Florida conditions spraying with contact insecti- 

 cides, especially oil emulsions, was effective. 



EXPERIMENTS. 



In order to test certain of the oil sprays under California conditions, 

 an experiment was conducted at Marysville on December 7, 1914. In 

 this experiment, which was not at all extensive, the following sprays 

 were used: Miscible oil No. 1, at the strengths of 5, 6| and 10 per cent; 

 "Black Leaf 40," 1 part to 400 parts of water; "Black Leaf 40," 

 1 part to 1,500 parts of water, and distillate emulsion, 3 per cent ; dis- 

 tillate emulsion 5 per cent strength; and "Yel-Ros," 2^ per cent 

 strength. 



The first examination of the trees sprayed in this experiment was 

 made on December 19th. Weather intervening between time of spray- 

 ing and time of examination was cloudy and damp, and results were 

 not apparent, but many of the insects were discolored, showing that 

 they were dead. A subsequent examination was made on January 19th, 

 which showed that all strengths of miscible oil and distillate emulsion 

 had done good work. Other experiments w^ere negative. While all 

 these tests Avere made in a small way, they indicated that at the strengths 

 used results could be attained, and therefore served as a basis for 

 future work. 



PRUNING. 



Some of the trees that needed spraying were very large, pruning 

 had been neglected and the general condition was such as to make 

 spraying exceedingly difficult. Consequently a man was hired to prune 

 some of the largest and most difficult to spray. 



SPRAYING. 



The work of spraying began on February 15th, and on account of 

 delays due to rain and mud was not finished until March 16th. Miscible 

 oil No. 1 was used at 6 per cent strength, with the addition of 2 quarts 

 of liquid whale oil soap to 200 gallons of the spray. 



A power sprayer, equipped with a 150 foot length of hose, 10 foot 

 rod and suitable nozzles, and giving a pressure of from 180 to 200 

 pounds, was used. Spraying was done with the utmost care in all 

 eases, and the trees were thoroughly drenched, particular attention 

 being paid to the undersides of the leaves, where the white fly is most 



