396 



THE CANADIAN ENTOMOLOGIST. 



For the purpose of better emphasizing the result of our work 

 in the orchards, the table gives not only the actual crop, but also 

 a "theoretical crop." This is obtained by calculating the crops 

 which the orchard would have yielded had it followed the general 

 average for the Valley. For example, the crop for the entire Valley 

 in 1916, was 111% of the 1915 crop. The 1915 crop in the experi- 

 mental orchard was 560 barrels; therefore, the theoretical crop 

 could be 621 barrels, though the actual crop was considerably below 

 that figure, viz., 300 barrels. By comparing the theoretical crop, 

 obtained in this way with the actual crop, we find that up to and 

 including the year 1913 the crop in the orchard is better than the 

 average, but in 1914, it dropped below and continued to do so 

 every year until 1917. This period corresponds with the increas- 

 ing severity of the infestation of the Green Apple Bug as shown 

 by actual observation. The figures for the three leading varieties 

 show in a very striking manner the steady falling off in yield, and 

 no one who watched the work of the pest in the orchard could 

 doubt that it was the cause of the decline. In 1917, the year the 

 treatment was given, the crop for the entire Valley was 109.26% 

 of the previous crop, while the crop in the orchard was 406.9% 

 of the crop of the previous year. Expressed differently, the actual 

 crop was 1,469 barrels, while the theoretical was 393 barrels. 



PERCENTAGE OF DIFFERENT GRADES OF ALL VARIETIES 

 IN ENTIRE VALLEY AND IN EXPERIMENTAL ORCHARD 



Table No. 2. 



