49 



ima the length of the life cycle of the insect. In the records given 

 we find that the periods vary from 40 to about GQ days, with an aver- 

 age of 55 days, or about 8 weeks. Professor Gillette finds that 

 according to his life history studies upon the sunmier brood the 



Fig. 10.— Band record made by David Brother.? in Colorado in 1S99. 



period of the different stages is as follows: From Qgg to larva, 7 

 days; from larva to cocoon stage, 19 days; from cocoon stage to emer- 

 gence of moth, 18 da3^s; from emergence of moth to middle of Qgg^- 



FiG. 11.— Baud record publi.shed by Prof. C. P. Gillette, taken on 1-1 tree.s, at Fort Collins, Colo., in 1900. 



Ia3dng stage, 5 days (estimated); total, 49 days, or 7 weeks. Fj-om 

 the writer's numerous records of the lengths of the different stages, 

 however, it is found that most are somewhat longer than those given 

 6514— No. 41—03 4 



