152 



DECIDUOUS FRUIT INSECTS AXD INSECTICIDES. 



FIRST BROOD OF PUP.E. 



Time of pupation and length of pupal stage. — The larvae for this 

 record were collected from banded trees and placed in gelatin capsules 

 and vials to obtain pupation records. Practically no difference in 

 length of pupal period was found in those kept in capsules and in 

 those in vials. Of the 123 larvae placed for pupation 52 died, and 

 of the 71 remaining 12 elected to pass the winter as larvae. The 

 pupation record in Table XL is therefore recorded from only 59 indi- 

 viduals. The earliest pupa occurred July 8, the latest August 16; 

 the earliest adult issued July 27, the latest September 13. Conse- 

 quently the pupal period ranged from July 8 to September 13, a 



Fig. 34. — Diagram showing first-brood pupae, 1911. (Original.) 



period of 68 days. The shortest pupal stage was 18 days, the longest 

 37, and the average 23.12 days. Using this average we find that 

 probably the earliest pupa occurred July 4, and as the latest adult 

 (see adult emergence record, Table XLIII) issued September 29 we 

 have a theoretical range for the pupal period of 87 days. 



Of the larvae under observation there were 21 males and 33 females, 

 the average pupal stage of the former being 22.95 days and that of 

 the latter 23.45 (see Table XLI), the females thus requiring half a 

 day longer to develop into adults. Five individuals escaped before 

 their sex could be determined. 



Figure 34 shows graphically the time of pupation of the first brood. 



