36 



Corn and grass. 



[1899 



The progress and effect of this larval infestation are thus described 

 by Prof. Osborn, U.S.A.,* in his recent most valuable condensation of 

 information up to date on Hessian Fly attaclv : — 



" In autumn the eggs are laid upon the early appearing leaves, and 

 the passage of the larvae down the sheath carries them down to or 

 below the surface of the ground, often very near to the root itself. 

 Here their presence causes more or less swelling of the base of leaf 

 and culm, scarcely enough to be counted a gall formation, but the 

 immediate effect seems to be a stimulus at the point of attack." 



The above describes the effect of infestation on autumn or winter 

 Wheat before the plant has developed ; in the case of presence on the 

 spring Wheat when the stalk has grown, it is very much more notice- 

 able. In tliis state of irrowth the maggot makes its way similarly 



Attacked Barley-stem: 1, bent down ; 2, showing " flax-seeds." 



down the leaves, but there under the sheathing-leaf it takes a position 

 commonly above the first or second knot, and ends its locomotive life. 

 It remains fixed at one spot, feeding on the juices of the stem, which 

 thus becomes weakened at the place of suction, until it bends, or 

 "elbows" down, as shown in the figure, drawn from life by myself. 



By this — that is, by the "elbowing," or bending down of the straw 

 at an acute angle — the Hessian Fly infestation may be easily distin- 

 guished from all of our other corn stem infestations, and also the 



• See ' Hessian Fly in the United States,' by Prof. Herbert Osborn, p. 27 ; 

 Bulletin No. 16, New Series, U.S. Dept. of Agriculture, Washington, 1898. 



