148 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



orchard sufficiently wormy for satisfactory use. But by this time 

 practically every commercial orchard in the vicinity was well sprayed. 



In the meantime, in an adjoining county, a number of young com- 

 mercial orchards were growing up in the midst of old, mixed and exceed- 

 ingly wormy ones. Work Avas therefore postponed until these or- 

 chards came into good bearing. Last season three of these orchards 

 were selected for use. They were located, in a triangle, approximately 

 fourteen miles apart, on different sides of a valley and represented 

 different climatic conditions. They were all extremely wormy, as the 

 records will show, but varied in the number of worms and the number 

 of apples per tree sufficiently to represent three different conditions 

 of infestation. 



As many of the methods used in this study have been criticised in 

 recent papers before this society, it seems necessary to discuss method 

 before discussing results obtained by their use. The writer has pre- 

 pared another paper on the subject of "Methods in Codling Moth 

 Study" to be presented later, which deals with these matters at lenglh 

 and to which the reader is referred for extended discussion of these 

 questions. 



The following suggestions and conclusions taken from this paper 

 will be helpful in studying the results here presented. 



1st. The driving spray, as presented by the writer, is a method of 

 spraying, and not the result of the use of certain apparatus. Its 

 three essentials are, power sufficient to drive into the calyx cavity, 

 position above tree so as to be able to direct the spray straight into 

 each blossom, and perseverance in application until every single blos- 

 som on every tree in the orchard has been properly treated. 



2d. That all results presented by the writer are from that method. 

 Comparisons have been made between sprays, but not between meth- 

 ods. 



3d. Accurate comparison of methods is well nigh impossible, at 

 least until considerable work has been done in standardizing apparatus 

 and testing mechanical efficiency of nozzles, etc., under different 

 pressures and at different distances. 



4th. The driving spray method does not advocate any particular 

 numbers of sprays; from one to five are found necessary under differ- 

 ent conditions. It, however, does advocate a less number and a higher 

 individual efficiency than previously employed. Likewise, it does 

 not advocate any particular amount of poison, though, in the writer's 

 experience, the highest efficiency has not been reached with less than 

 four pounds of lead arsenate to 100 gallons. 



5th. Two distinct systems of checking are in use. 1st, the unsprayed 

 plot, which may be located at one end, or in the center. If at one 



