THE CODLING MOTH ON PEARS IN CALIFORNIA. 39 



To show more fully the results of the different sprayings as influenc- 

 ing the places of entrance of the worms and showing where they are 

 mostly killed Tables XXXIV, XXXV, and XXXVI have been pre- 

 pared, which are in part summaries of the foregoing tables and of 

 those which are to follow under the heading of "Commercial results 

 from spraying." 



In Table XXXIV, in the unsprayed portion, Plat VI, 85.702 per 

 cent of the pears were wormy at the calyx, and 8.198 per cent were 

 wormy at the side and stem, while in the demonstration block, Plat I, 

 which received three sprayings only, 0.223 per cent of the pears were 

 wormy at the calyx.and 3.803 per cent at the side and stem. This indi- 

 cates that the sprayings reduced the infestation at the calyx from 

 85.702 per cent to 0.223 per cent, a reduction to approximately one 

 three-hundred-and-eighty-f ourth of the original infestation. That is, 

 the check plat showed 384 times more pears wormy at the calyx than 

 was the case with Plat I. The infestation at the side and stem was 

 reduced from 8.198 per cent on the check plat to 3.803 per cent for 

 Plat I, a reduction of only a little over one-half of the original infes- 

 tation. While the infestation at the calyx was reduced 384 times, 

 the infestation at the side and stem was reduced only 2.4 times. 



Plat II, which received the two early sprayings for the first-brood 

 worms, but no late spraying corresponding to the third treatment on 

 Plat I, had 0.747 per cent of the pears wormy at the calyx, indicating 

 a reduction to about one one-hundred-and-fourteenth of the original 

 infestation, while the infestation at the side and stem was not reduced 

 but apparently slightly increased, as this plat showed 9.943 per cent 

 of the fruit wormy at the side and stem as against 8.198 per cent 

 wormy at the side and stem in the unsprayed check plat. 



This phenomenon might be thought to indicate that there was some 

 repellent action by the arsenate of lead in the calyx cavity to cause 

 the worms to seek the uncoated surface of the pear. However, this 

 is probably explained by the fact that on the unsprayed block such a 

 large portion of the pears were injured by the first-brood worms and 

 fell off the trees before the appearance of the second-brood worms, 

 that, although the same proportion of worms of this second brood 

 entered the side of the fruit in the check block as in the block receiv- 

 ing the two early sprayings, there were not enough pears left on the 

 trees in the check block to bring the average of the total crop of 

 pears, wormy at the side, up to that of Plat II, where a much larger 

 portion of the year's crop had been kept on the trees by the early 

 sprayings. This same condition holds true for the unsprayed check, 

 Plat IV, in Table XXXV, recording experiments at Suisun in 1910. 

 More than 60 per cent of the total crop of fruit from the check plat 

 dropped from the trees, due almost entirely to the work of the first- 

 brood worms. On the sprayed blocks only 13 to 22 per cent of the 

 total crop of fruit dropped from the trees. 



