STATE AGRICULTURAL SOCIETY. 
823 
HESSIAN FLY. LARVA. 
younger twelve can usually be perceived, lhese segments aie 
but slightly indicated, the sutures between them forming faint 
transverse lines of a greenish brown hue. Its under side is flat¬ 
tened and shows in the middle an oblong grass green cloud from 
internal visceral matter. No impressed lines or constrictions 
are perceptible at the sutures at first, but after the worm has 
laid exposed to the air an hour or more, the color of the trans¬ 
verse lines above mentioned, vanishes, and then, perhaps tiom 
becoming, somewhat dried, faintly impressed and very slender 
lines may be perceived at the sutures; and faint longitudinal 
lines or strise are also discernable, as though produced by the 
pressure of the parallel veins or ribs of the sheath and the cen¬ 
tral stalk between which the worm had laid. 
The autumnal attack of the Hessian fly is in a double sense a 
radical one. Each particular shoot at whose root one or more 
of these larvse nestles, is commonly destroyed, by the time the 
worm has attained its growth and leaves off feeding. The pres¬ 
ence of these insects therefore, is readily detected by an exam¬ 
ination of the young wheat in October or November. Individual 
shoots will be found here and there in the field, withered and 
changed to a light yellow color, as represented, plate 3, fig. B,f 
strongly contrasting with the rich green of the vigorous uninjured 
plants, as shown in the same figure at *. The frost or some other 
casualty may cause the ends of some of the other leaves to be ol 
a pale yellow color, but here the whole plant is of that hue ; and 
where a field is badly infested, this yellow, sickly aspect may be 
discerned at a distance. On examining the withered plants, the 
worm, or flax-seed if it has advanced to that stage, can be leadily 
found. It is situated a short distance below the surface of the 
earth, at the crown of the root. One or two radical leaves stait 
from this point, their bases forming a cylindrical envelope or 
sheath around the central or main shoot, which as yet is only in 
its infancy. It is within this sheath, at its base, that the worms 
repose, one, two, three or more, and by imbibing the nutritious 
juices of the tender young shoot, cause it to wither and die. 
The mechanical pressure of the larva;, which writers have so 
frequently spoken of as impeding the circulation of the fluids of 
the plant and thereby causing it to perish, J think has had too 
much importance assigned to it. The young plants are so soft 
and pliant that they would readily accommodate themselves to 
