36 



BULLETIN 429, tJ. S. DEPAETMENT OP AGETCULTUEE. 



Ill order that observations might be made during the period of 

 cocooniiig and at the time of pupation without disturbing the speci- 

 mens in their normal manner of procedure, small strips of wood 

 mth shght partitions between them were used, held together by- 

 paper cHps bent at a convenient angle. Over the partitions was 

 pasted a thin film of mica with a sprinkling of fine sawdust under- 

 neath. This device, described in previous pubhcations of the bureau, 

 proved to suffice throughout the period of experimentation. 



Figure 7 is an illustration of the strips of wood used. 



Fig. 7.— Device used to obtain pupal records of the codling moth. (Hammar.) 

 THE SPRING BROOD. 

 SPRING BROOD OF PUP^. 



Time of pupation. — The first record of pupation of overwintering 

 larvae took place March 23, and from that date pupation continued 

 more or less regularly for a period of 51 days, the last pupation 

 recorded occurring on May 13. 



Length of pupal stage. — The length of the pupal period of the spring 

 brood has a range of from 12 to 36 days, the majority of the indi- 

 viduals, however, completing the stage after 26 days had elapsed. 

 The average for the entire time is found to be 22.97 days. (See 

 Table XXXII.) 



