THE HESSIAN FLY. 9 
utilized them, placing an enormous number of eggs on the upper 
surface of the leaves, precisely as is their wont in the case of grains. 
The larvee, after making their way down the sheaths and beginning 
to attack the plants, gave to them precisely the same appearance as 
infested wheat plants. Under these circumstances the Hessian fly 
appeared to breed as freely in Agropyron smith as in wheat. On 
October 25 of the following year Mr. G. 1. Reeves found many Hessian 
fly eggs and larve in all stages of development up to the flaxseed on 
Agropyron repens, and prebably also on other varieties of this grass, 
growing up in the wheat fields in the vicinity of Vancouver, Wash. 
Mr. C. N. Ainslie found the flaxseed stage of the Hessian fly in Agro- 
pyron tenerum growing in alleys at Elk Point, S. Dak., June 23, 1913. 
There is therefore no doubt whatever but that the Hessian fly will 
breed in Agropyron, and perhaps also, in some portions of the coun- 
try, to a limited extent, in Elymus, Agrostis, and Bromus. Dr. S. A, 
Forbes a number of years ago failed to induce the fly to breed in 
either redtop, bluegrass, foxtail, or orchard grass. 
EFFECT OF LARVAE ON THE PLANT. 
The effect of the larve on a young wheat plant is very marked and 
becomes observable soon after the young reach the stem under the 
sheath. Once he has observed it, any farmer can readily detect an 
infested plant, or a single infested tiller may be as readily detected in 
a cluster without taking the trouble to remove the plant from the 
eround.>)- - 
For the purpose of comparison, illustrations are given of an unin- 
fested young plant (fig. 9) and an infested young plant (fig. 10). An 
uninfested plant is of a more slender growth, the green color is lighter, 
with a slight tinge of yellow, the stems are more or less visible, and 
the central unfolding leaf is present. The whole plant is inclined to 
droop and the tillers spread out and cover the ground. An infested 
plant is without stem and the leaves are broader, usually shorter and 
of a deep bluish-green color, somewhat resembling those of oats. The 
plant stands more erect, and, in fact, is but a mass of short overgrown 
leaves that usually kill with the first frost. Figure 10 shows a young 
tiller starting out from below the part attacked by the fly. If this 
tiller were to be attacked after it appeared above ground, there would 
follow the same appearance as in case of the original plant; that is to 
say, the leaves would become broader and of a darker color. The 
foregoing statement will apply to a severe attack on fali wheat in 
spring and on young spring wheat. The only exception in the appear- 
ance of infested young plants is in the case of the hard wheats, whose 
foliage is broader and of a darker color, but the erect position will 
still enable the observer to detect the infestation. Of course later on 
69743°—Bull. 640—15——2 
