64 N. 11. AGR. EXPERIMENT STATION f Bulletin 143 



bark or in the crevices of the trunk, but often cocoons are made 

 under boards, or in an apple barrel or bin. In a careful examina- 

 tion of seven trees it was found that 70 per cent, of the cocoons 

 are on the trunk and that the remainder are found on some 

 of the larger and rougher limbs at an average distance of about 

 S feet from the crotch. More of the cocoons are on the lower than 

 on the upper part of the trunk, as when the caterpillars leave 

 the dropped apples they crawl up the trunk and make their 

 cocoons at the first suitable points. 



Only from 5 to 20 per cent, of the larvje survive the winter. 

 An examination of seven trees, which averaged 38 cocoons per 

 tree in the fall, showed but 5 per cent, alive in the spring, 87 

 per cent, having been killed by birds, 4 per cent, by disease and 

 3 per cent, by cold. In another orchard 1,096 cocoons were exam- 

 ined in INIay, 1907, with 19 per cent, alive, 66 per cent, having 

 been killed by birds, 6 per cent, by disease and 9 per cent, by 

 cold. It is quite evident that the birds, particularly the downy 

 woodpeckers and the nuthatches are the most important enemies 

 of the codling moth in New England and that they should be 

 given every protection and be attracted to the orchard in every 

 way possible. 



The Transformation. During INIay or early June, the cater- 

 pillar opens the end of the cocoon and spins a silken tube from it 

 to the surface. Then retiring to the cocoon, with its head 

 towards the opening, it sheds its winter clothes, transforming 

 into a pupa. The pupa is a dormant stage in which the insect 

 has almost no power of motion, and shows but little sign of life, 

 but during which wonderful changes in its structure are going 

 on, so that from the old tissues of the worm-like larva are formed 

 the organs of the active, winged moth. In 1906 pupation com- 

 menced May 7, the last larva did not pupate until early in June, 

 but the average date was May 25. In June, 1907, the average 

 date of pupation was June 16 or three weeks later, while in 1908 

 the average date was June 1, the first pupa being on May 20 

 and the last June 9. The time of pupation is therefore seen to 

 vary greatly with the season, but with average weather condi- 

 tions to occur about June 1. 



The time passed in the pupal stage also varies with the sea- 

 son and the time whon the i)upa is formed. Pupte formed in 



