THE CODLING MOTH IN MASSACHUSETTS 67 



Calyx Spray. This is tlie most important spray to combat the codling 

 moth in Massachusetts. It is applied between the time when about 90 per 

 cent of the blossom petals have fallen and the time when the calyx lobes 

 have closed, a period of seven to ten days depending on the weather. 

 Plate II shows the appearance of the fruit during this period. Spraying 

 while the trees are in bloom is unnecessary. For a few days after the petals 

 have fallen, the calyx lobes are laid back in such a way that the cavity con- 

 taining the stamens and pistils of the flower is open and can be filled with 

 drops of poisoned spray, thus forming a mortal barrier to any worm which 

 attempts to enter the fruit through the calyx cavity at any time during the 

 season. There are no worms attacking the apple when this spray is applied 

 but the caljTc cavity offers excellent shelter from wind, sun, and natural 

 enemies while the larvae are entering the apples, and experiments show that 

 60 to 80 per cent of them take advantage of this protection. 



Cover Sprays. The function of cover, or post-calj'x, sprays is to place 

 over the surface of the fruit a protective film which will kill codling moth 

 larvae when they attempt to enter through the side. Theoretically these 

 sprays should be applied just before the larvae of each generation hatch and 

 attack the fruit in large numbers, as is shown diagrammatically in Figure 2. 

 In both 1923 and 1924 large numbers of larvae of the first brood hatched 

 approximately twenty days after the calyx spray was a^Dplied, while in 1925, 

 due to extremely high temperature, this condition was reached about four- 

 teen days after the Calyx spray was applied. In 1924, however, cold 

 weather so effectively delayed development that the greatest number of lar- 

 vae of that brood hatched about forty-five days after the calyx spray. 

 From this, it is evident that the most effective time to apply cover sprays 

 must be determined each year, but that with average development this 

 period for the first brood larvae will occur about three weeks after the 

 calyx spray. Figure 2 also shows the time of hatching of the second brood 

 larvae in the three seasons when this development was studied. In the well- 

 cared-for Massachusetts orchard, the second brood larvae are usually not 

 abundant; and the latest spray recommended is No. 7, eight weeks after the 

 calj-x, in order to combat the apple maggot effectively. This also gives some 

 protection against the attack of second brood codling moth larvae, without 

 the danger of arsenical residue on the fruit at harvest time. 



Spray Schedule for the Control of Apple Pests in Massachusetts 



The following spray schedule will serve as a basis for spraying apples in 

 Massachusetts. Dusts are not included in this calendar on account of the 

 fact that many experiments indicate superiority of the spray to control a 

 heavy infestation of codling moth. In the average orchard, the first four 

 sprays listed below are advisable. In addition to the four essential sprays, 

 one or more of the special sprays, Nos. 5, 6 and 7, are necessary when the 

 pests indicated are unusually abundant, or abnormal weather conditions 

 make additional protection against them advisable. Fruit growers should 

 secure all the information possible and then use their own judgment as to 

 which of these, if any, they may need to apply. 



