HESSIAN FLY. 
37 
Wheat: no perceptible damage/’ “ No damage noticeable.” “Larvae 
and puparia in every field, but sparingly.” “ In several fields, damage 
immaterial; in no case one per cent, of damage done.” In two localities 
about 17 miles apart, “ in neither case had any damage of consequence 
been done.” 
In the observations of the past as well as of those of previous 
seasons, the vigorous and healthy state of the crop is noticed as an 
important help in lessening amount of attack, or consequent injury, 
and a few observations are given as to results on various kinds of soil, 
or where nature of locality, as shade, affects the health of the crop. 
Full details of the method of Hessian Fly attack, and also measures 
found useful both for lessening amount of infestation, and for lessening 
its injurious effects on the attacked Corn, have been given so repeatedly 
since the autumn of 1886, that they are thoroughly before the public. 
Destruction of infested screenings .—Some remarks, however, may 
still be usefully made in confirmation of the most important preventive 
measure of all, namely, destroying the “flax-seeds” (that is, the 
chrysalids or puparia of the Hessian Fly), when they are thrown down 
by thrashing-machines amongst the light screenings from infested 
Barley or Wheat straw. 
In these circumstances, what (according to our own treatment) will 
or will not be the origin of future attack, lies in our own hands. If 
the light screenings with their contents are destroyed (which may be 
done with no loss of material, and scarcely any labour) there is a clear 
end of the matter. If, on the contrary, the screenings are preserved, 
the insect contents, whether Hessian Flies or their parasites, will go 
forth, and we allow another year’s mischief to take place. 
The parasite attack does not prevent the infested pest living on the 
straw up to the change to the chrysalid or flax-seed state,* so that it 
appears to make little difference practically whether the Hessian Fly 
maggot damages the straw simply for its own feeding, or to support in 
addition the parasite maggot within it. In either case we submit to 
another year’s attack which might have been spared. 
Another form of the same plan of preservation which has been 
theoretically advocated is breeding the various contents of the flax¬ 
seeds, and selecting the parasites to turn loose. But this would involve 
great risk. None but well skilled entomologists can tell with certainty 
amongst these excessively minute creatures whether it is pest or para- 
* This point is clearly shown by the observations of Dr. C. Lindeman, the great 
Russian authority on the habits of the Hessian Fly, who has himself bred the 
following parasitic flies from Hessian Fly puparia, namely,— Merisus intermedins; 
Tetrasticus rileyi; Semiutellus nigripes; Eupelrnus karschii; Platygastev minutus , 
and j Euryscapus saltator; all these species have been identified by Prof. C. V. Riley 
as present parasitically in this country. 
