December, 1909.] the codling MOTH. 73 



thirds of a pound of Paris green per barrel showed no material 

 increase in effectiveness over one-third of a pound. 



3, The Best Time to Spray. It has been generally conceded 

 that the spraying just after the blossoms drop is the most impor- 

 tant in fighting the codling moth, from the fact that two-thirds 

 of the young caterpillars (see page 68) of the first generation 

 enter the apples through the blossom or calyx end. The object 

 of the first spraying is, therefore, to deposit poison in the calyx 

 cavity, so that when the little worm enters and feeds in the cavity 

 it is killed. It has always been recommended to spray before 

 the calyx lobes close. Observation shows that in New Hampshire 

 the calyces of the Baldwin apples (fully 90 per cent, of our 

 apples are Baldwins) close about a week to 10 days after the last 

 blossoms have dropped. In other varieties the calyx remains 

 open longer. If the trees are sprayed after the calyx is nearly 

 or completely closed, little or none of it gets into the calyx cavity, 

 and the only effect from it is from that which remains on the 

 foliage. In one orchard, where the first spraying was done after 

 the calyces were partially closed, we secured practically no benefit 

 from it, and correspondents who have given but one spraying 

 ten days to two weeks after the blossoms drop have had the same 

 experience. 



"Where the first spraying is given within a week after the last 

 blossoms fall and no other spraying is given, 82 per cent, of the 

 ■worminess found on unsprayed trees may be prevented; i. e., 

 if unsprayed trees had 60 per cent, of the fruit injured by worms 

 during the whole season, trees given but one spraying would have 

 but 11 per cent, wormy. This does not refer merely to the wormi- 

 ness of the picked fruit, but to the amount of both windfalls and 

 picked fruit injured, for 11 per cent, wormy during the whole 

 season would mean not over 5 per cent, of the picked fruit 

 "wormy. 



Second Spraying. From the fact that one-third of the worms 

 do not enter the fruit through the calyx it is evident that they 

 cannot be killed by poison applied in the calyx cavity. As has 

 been noted (see page 67), when the caterpillars hatch they feed 

 a little on the. foliage before entering the apple. It is evident, 

 therefore, that by applying an arsenical spray to the foliage 

 young caterpillars feeding upon it may be killed. Thus the spray 



