April, '08] JOURNAL OF ECONOMIC ENTOMOLOGY 129 



PRELIMINARY REPORT ON THE LIFE HISTORY OF THE 



CODLING MOTH AND SPRAYING EXPERIMENTS 



AGAINST IT 



By E. DwiGHT Sanderson, Durham, N. H, 



For the past three years we have been working on the life history 

 of the codling moth in New Hampshire, and making experiments to 

 determine the value of spraying at different times. The greater part 

 of the life history work was done by Dr. T. J. Headlee or was under 

 his immediate charge, as was also much of the field work. 



It is convenient to commence the consideration of the life history 

 of an insect with a discussion of its wintering habits and then follow 

 it thru the season. Seven large apple trees were thoroly examined 

 by a competent student last spring to determine the position in which 

 the codling moth larvae hibernate and their mortality. An average of 

 55 cocoons per tree were found, 70% being on the trunk and 30% on 

 the limbs. Records showing the height of the cocoons on the trunk 

 indicate clearly that more cocoons are to be found just below the 

 crotch and just above the base of the tree, than are to be found midway 

 on the trunk. It seems very evident that the larvae descend from the 

 limbs to the trunk and ascend from the dropped apples on the ground 

 to the lower part of the trunk to form their cocoons. Eighty-seven 

 per cent were kiUed by birds, 4% by fungus disease, 3% by cold, and 

 but 5% remained alive. An examination of numerous other trees in 

 the same orchard including the cocoons of 1,086 larvae showed that Q%% 

 had been killed by birds, 9% by cold, 6% by fungus and 19% were 

 alive. The percentage of mortality will of course vary with local 

 conditions, but previous experience reinforces these observations that 

 only a very small percentage survive hibernation. 



In the spring a short tube is spun out from the cocoon prior to pu- 

 pation. In 1906 the average date of pupation for 43 larvae was May 

 25, the average length of the pupation stage 20 days, the majority of 

 adults appearing about June 14. In 1907 the average date of pupa- 

 tion for 103 larvEe was June 16, the average length of the pupal stage 

 being 16 days and the majority of adults appearing about July 2. It 

 is interesting to note the difference of four days in the pupal stage in 

 the two seasons. We have not studied the temperature data with suf- 

 ficient care to determine whether the difference is due to temperature, 

 but such a result shows the necessity for having a large series of indi' 

 viduals upon which to base our conclusions as to the life history of an 

 insect, and also the importance of studying it for several years if its 

 economic importance warrants it. The length of the pupal stage 



