April, '11] WEBSTER: wheat-head army-worm 183 



had been pastured in the spring and fall of every year, 6.1 per cent 

 of the heads were injured, in a count of 1,500 heads. Another meadow, 

 pastured only in the fall, showed 3.6 per cent injured heads. 



In a one-year-old clover and timothy field at Dexter, Iowa, 28.6 

 per cent injured timothy heads were found in 1909. That fall the field 

 was heavily pastured, and the larger part of it was plowed in the 

 spring and put into corn. On July 1, 1910, only 10.2 per cent of the 

 timothy heads were injured in the part of the meadow that remained. 

 But the greater part of the field had been turned under that spring. 

 The moths that emerged in the spring, then, would deposit their eggs 

 in the timothy that remained. Had the field been left unplowed, the 

 average injury in 1910 would doubtless have been much less than 

 10.2 per cent. 



Two meadows near Ames, one pastured and the other unpastured, 

 were compared in the fall of 1910. Both were badly infested that 

 summer. Stock were put in the one field between September 6 and 

 10, and they ate the grass down fairly close within ten days or two 

 weeks. October 4 this field was compared with the unpastured field, 

 and an amazing contrast was found between the two. No larvae were 

 found in the pastured field, but they were quite common on the second 

 growth of timothy in the other field. This second growth had been 

 kept well eaten down in the pastured field. Later observations showed 

 the same result, no larvae in the one field and injured timothy heads 

 and plenty of larvae in the other. 



If a meadow is to be pastured, stock should eat dowTi the infested 

 fields fairly close during the first half of September, certainly before 

 the 15th. Where timothy and clover are grown together, care must 

 be taken that the pasturing is not so close that the clover is exposed 

 to injury during the winter. A field might be pastured fairly close 

 before the middle of September, and left free of stock the rest of the 

 fall, giving the clover some chance for growth after that time 



To summarize, fall pasturing is the best measure that we know of 

 against the wheat-head army-worm in timothy; early fall plowing 

 and clean culture are measures next in importance. 



President Sanderson: Discussion of this paper? 



Mr. Smith: I should like to ask Mr, Webster how many adults he 

 bred. 



Mr. Webster: Thirty or forty. 



Mr. Smith: The reason I ask this question is that in our experi- 

 ments we have found out that only a very few could be actually raised, 

 and so got very little information as to species, and as a matter of 



