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Annals Entomological Society of America [Vol. XV, 



specimens of fly were examined as found and the percentage 

 of these larvae and puparia noted. In one field, pupariation 

 of these larvae began on November 22, was half completed by 

 December 9, and completed January 4. In another field, 

 pupariation began December 2, was half completed by January 

 4 and completed February 28. Pupation of these larvae in 

 both fields began March 18 and was practically completed by 

 April 10. A very small number of larvae remained to produce 

 stragglers or to hang over until fall. Adults began emerging 

 March 29 and continued throughout April. 



Fig. 3. Graph showing the pupation of Hessian fly of the 

 "late wave" 1920. 



By a study of puparia, offspring of the normal emergence 

 the preceding fall, it was determined that pupation and 

 emergence occurred on approximately the same dates as in the 

 case of "hang-over" and "late wave." Thus the pupation of 

 larvae and the emergence of adults of all Hessian fly in the 

 spring of 1921 took place at about the same time, regardless 

 of their origin. 



