8 INJURIOUS INSECTS OF 1903. 



lowing spring. Volunteer in plowed land adjoining infested 

 fields, and undisturbed volunteer along the edges of fields, may 

 both furnished their quota of flies the following "season. Of 

 course the freezing down of these volunteer plants during the 

 winter would not kill the contained "flax seeds" any more than 

 the cold would afifect those in the stubble. While we can say 

 with confidence, from our discoveries this season, that there is 

 more than one brood in Minnesota, too hasty conclusions must 

 not be drawn as to the actual number of broods, since the 

 weather may have a marked effect in this direction. 



Fig. (i. — Wheat Plant used in breeding jar, showing eggs on leaf; one egg in outline, 

 enlarged about 70 times, and pupal skin protruding from puparium four times 

 enlarged. Original. 



One farmer declares that fall plowing will not kill the fly, 

 stating that he kept wheat off his fields for two years and sum- 

 mer-fallowed the year preceding wheat, yet his next planting was 

 very seriously affected. In response to my query about his 

 neighbors, he said there might have been neglected stubble one- 

 third of a mile away, but no nearer. The explanation of this 

 infection can be found in the fact that the flv mav have been 



