108 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



Table XIX. — Percentages of fruit free from injury by the codling moth and plum cur- 

 culio on one-spray, demonstration, and unsprayed plats in Virginia, Michigan, 

 Delaware, and Kansas, in 1910 and 1911. 



In Table XX is given a summary of the results of the one-spray 

 experiments carried out by this bureau in 1909 (Bui. 80, Part VII, 

 Revised) for the purpose of comparison with the foregoing results of 

 the 1910 and 1911 experiments (Table XIX). 



Table XX. — Percentages of fruit free from injury by the codling moth and plum curculio 

 on demonstration, one-spray, and unsprayed plats in Arkansas, Virginia, and Michigan 

 in 1909. 



In comparing Tables XIX and XX it will be seen that for the two sets 

 of experiments the average percentages of fruit free from codling- 

 moth injury on the sprayed plats were practically the same, while on 

 the unsprayed plats the fruit was considerably less infested with this 

 insect in 1909 than in 1910 and 1911. The average percentage of 

 fruit free from this insect for the demonstration treatment in 1909 

 was 96.57 per cent as against 96.72 per cent in 1910 and 1911, a dif- 

 ference of only 0.15 per cent. In the case of the one-spray treatment 

 there was a difference of only 0.70 per cent in the average percentages 

 of fruit free from codling-moth injury. 



Table XXI shows the total efficiency and the protection afforded 

 to each of the different parts of the apple by the treatments for the 

 four orchards. It will be seen from the average of the four localities 

 that nearly 60 per cent of the total larvae on the unsprayed plats 

 entered through the calyx, while on the sprayed plats 83 per cent of 

 the worms entered the fruit by way of the side, showing that the poison 

 in the calyx is much more efficient than that on the side of the fruit. 



