164 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 10 



to support this idea, but clearly indicates that the individual grower 

 usually does realize a large measure of protection regardless of the 

 action taken by his neighbors." 



Field Observations on Migration 



The writer's attention was first called to the fact that the wind 

 might be an active factor in transporting the adult flies while studying 

 the dissemination of chinch bugs from winter quarters in the spring 

 of 1913. On April 20, while counting the number of chinch bugs 



:'-'.VV-.''.v6Hi5>i'3''.;- 



.-. ••-9-; iiVii- ■..■■•. 



:■■'■' IO-3->3 





A 



\0-8-lJ 



F 



IO-5-Vj 



Fig. 6. Map of fields at McFarland, Kansas. Shaded area is that seriously in- 

 fested at harvest. 



arriving on an upright screen, a female fly was found blown against 

 the screen. The wind was from the east at the time and the nearest 

 infested field in that direction was over one mile away. Later on two 

 more females were taken in the same way. 



During the spring of 1914, considerable field data were collected, 

 tending to show that the flies were being distributed by the wind. In 

 May, 1914, the writer was requested to investigate an infestation of fly 

 in a wheat field north of Paxico, Kansas. This field had been planted 

 about October 10, 1913, on corn land located in the center of a large 

 pasture. The nearest field of wheat or wheat stubble was about one 



