THE MONTHLY BULLETIN. 



645 



mean the loss of two seasons' crops should be sufficient to impress upon 

 any orchardist the necessity for using control measures just as soon 

 as it appears. 



Control. 



Adequate means of control have now been worked out, and the dam- 

 age that has been done in certain sections in the past, where there has 

 been an outbreak of this serious insect, may be averted in the future. 

 Certain sprays have proven to be effective in destroying the egg, still 

 others the larva?, and the orchardist who will do the spraying thor- 

 oughly with the materials recommended need have little fear of failure 

 in protecting his crop. 



SPRAYS TO KILL THE EGGS. 



As the winter season is always spent in the egg stage, it was only 

 necessary to find some spray which when applied during the dormant 

 season, would kill them. A long series of laboratory experiments were 

 carried through by Prof. C. P. Gillette in 1895, and by the writer 

 in 1912; also a series of orchard experiments were conducted cluring 

 the latter year. In these it was found that an oil spray of some kind or 

 other, would penetrate through the tough, very impervious coating of 

 the egg mass, and kill the eggs beneath. Various strengths of kerosene 

 emulsion were used in the work with good results in some cases and 

 not so good in others. The variable results attained with this material 

 were such that it could not be recommended. Wliile in some cases an 

 emulsion containing a certain percentage of kerosene would kill all egg 

 masses to which it was applied, in others the same strength of material 

 in a different emulsion would fail to kill many of them. 



Miscible Oils. 



Nothing was found to be more effective in the work of killing the 

 eggs than the various brands of the commercial products known as 

 soluble or miscible oils. Of these preparations three kinds, viz, Target 

 Brand Scale Destroyer, Scalecide and Carboleine were used with splen- 

 did success. Applications were made with various strengths and the 

 results indicated that they should not be used weaker than one gallon 

 of soluble oil to nineteen gallons of water. Fig. 362 shows a sprayed 

 and unsprayed tree. The lower one was sprayed with Target Brand 

 Scale Destroyer one part to nineteen of water. 



This season before coming to California the writer helped in the work 

 of spraying for the control of this insect in the worst infested sections 

 of Colorado. In one of these every grower who was known to have 

 leaf-roller in his orchard sprayed. Remarkable results were attained 

 in all cases where spraying was thoroughly done. Some few people 

 tried to get along with from three to five gallons of spray per tree 

 where double the amount should have been used. They of course met 

 with a certain degree of failure. 



