13 



Under much the .same conditions I have reared the greatest nmiibers 

 of joint-worm flies, at present known as Isowma tritlcl Fitch, from the 

 Virginia r^^e grass {Elymus virginlcus^ fig. 2). In this case the grass 

 from which I secured these insects in greatest profusion came from 

 the most neglected roadsides. In the vicinity of the cit}' of Urbana, 

 111., I secured material from two localities, one quite near the resident 

 quarter, where the city government required the mowing off of weeds 

 and grasses, conuuencing in June, and the other farther from town, 

 along a neglected bank where the 

 grass was allowed to grow up un- 

 distur])ed year after year. From 

 grass stems from the former local- 

 it}^ I secured almost nothing, while 

 from that coming from the latter 

 locality 1 obtained enough to show 

 that there was here a constant 

 menace to the wheat fields in the 

 neighborhood. Now, as a matter 

 of fact, there is comparatively 

 little wheat or rye grown in the 

 neighborhood, and until I reared 

 these insects from the wild grasses 

 I could not account for their sud- 

 den appearance in the wheat and 

 r3^e fields, observed and recorded 

 in former years by Professor 

 Forbes and his assistants. What 

 has proven true here has been 

 shown to follow similar conditions 

 elsewhere in both Illinois and 

 Indiana. That is to say, where 

 farmers have allowed these grasses 

 to grow up al>out their farms year 

 after jq'ay under the impression 

 that they were not worth an}'^ attention, I have found the insects in 

 abundance, and also find that despite their otherwise good farming, 

 they have probably suffered more or less from the attacks of the 

 two species of destructive Isosoma in their grain, though they may 

 not have observed them or their subtile effects on the kernels of the 

 wheat and rye. I am convinced that there is an element of loss here 

 of which farmers are unaware and the precise effects of which they 

 do not therefore comprehend, 3^et might if they realized the situation. 



Virginia rye grass {Elymus vir^inicus) 

 (after Scribner) . 



