178 



Annals Entomological Society of America [Vol. XV, 



From a similar set of records made at Centralia, Illinois, 

 by Mr. W. B. Cartwright, of the U. S. Bureau of Entomology, 

 the crest of emergence of the "late wave" at that place was 

 determined to be on October 12, or five days earlier than at 

 Lafayette. From these two records of continuous observa- 

 tions, verified more or less by a number of fragmentary data, 

 it was determined that the emergence of the "late wave" 

 occurred in the reverse order to the normal, that is, it occurred 



Fig. 1. Graph showing Hessian fly egg counts made at Lafayette, 

 Indiana, September and October, 1920. 



earlier instead of later to the southward. The following map 

 (Fig. 2) indicates approximately the dates of emergence of the 

 "late wave" wherever it occurred in the section indicated. 

 From the latitude of Cincinnati southward these dates come 

 within the recommended safe sowing dates and for that area 

 the emergence can be considered normal. 



A study of pupation records for the beginning of the period 

 will also be quite interesting. These records were made by 

 frequent examination and dissection of flaxseeds in lots of one 

 hundred each, only those containing either larvse or pupae of 

 Hessian fly being included. In the graph of pupation (Fig. 3) 

 the number of pupae is indicated by the figures on the left 

 and the number of larvae by the figures on the right. 



