October, '221 



cartm'right: hessian fly host selection 



361 



above ground on September 10 to the period of injury by developing fly 

 larvae that the root systems of the individual plants were steadily en- 

 larging and that excessive tiller formation was becoming more pronounc- 

 ed. Rye in particular showed rapid tiller formation. Infestation 

 counts were made November 25th after the plants had reached the 

 maximimi growing period with the advent of winter. An adaptation 

 of the five linear foot method was used for selecting plants for examina- 

 tion. By this method samples are taken to include all plants from 

 five linear feet of drill row, each foot taken separately and at random. 

 Infestation data thus obtained are given in Table II. 



Table II — Infestation Data Sept. ], Sowing 



A detailed chart showing the infestation data for each individual 

 plant for the fall brood of flies is not possible on account of its large 

 size. However, a summary showing the more important features is 

 given in Table III. 



Table III — Sitmmary of Detail Infestation D.a.ta 



II. Sowing September 14. 



Plants of this sowing appeared above ground on September 20th. 

 From this date and throughout the period of activity of the Hessian 

 fly for the fall, ten plants were examined daily for each plot. Plants 

 were selected at random and the accumulated egg masses recorded. 

 Condensed results from the examinations are given in Table IV. 



