77te Progress of the Hessian Fly. 
483 
of cultivation to account for the affection of some fields and the 
immunity of others ; nor was there any appreciable distinction 
in this case between the attacked and the uninfested crops in 
respect of the vigour of the plants. In another part of Cam- 
bridffeshire the loss occasioned was estimated at four bushels 
per acre ; in this instance the wheat-plants were observed to 
lose plant at the end of November, and to look weak in the 
early spring. It was thought that wireworms were the cause, 
and the land was dressed with 1^ cwt. of nitrate of soda per 
acre and well rolled, without much beneficial result. The 
mischief was without doubt continuous throughout the early 
summer, as the straw was much scrawled and the ears on many 
of the infested stems merely contained " tail " corn. In the 
barley-field adjacent to these wheat-fields there was also con- 
siderable harm done to the plants. Evidently the flies of the 
spring generation hatched on the wheat-plants had flown to 
fresh fields and pastures new, and laid their eggs upon the 
barley-plants. 
As a rule, it was found this season that barley -plants were 
more injured than wheat-plants. The reason of this is that the 
barley-plants, particularly those sown late, were prevented by 
the drought from growing away from the attacks of the larvae ; 
the wheat-plants, on the other hand, were well established before 
the drought set in, and, as is well known, these plants are able 
to resist drought in ordinary conditions. The loss in the wheat 
crop on some wheat land in Bedfordshire was held to be equal to 
two bushels per acre. No failure of plant was noticed in the 
autumn. The seed was put in during tbe first week in Novem- 
ber, so that it may be assumed that the attack was not commenced 
until the spring, and that the flies which placed eggs upon the 
plants were those of the second generation, and came either 
from self-sown corn-plants in " seeds," or on the outsides of 
fields or from neighbouring wheat-fields. One or two wheat- 
fields in the vicinity were very slightly infested, appearing to 
have been attacked also in the spring. There were no other 
infested fields that could be discovered within some miles. It is, 
of course, possible that flies might have been borne by the wind 
from a long distance, as they carry a large amount of sail in 
the shape of wings, and would be wafted far and rapidly. 
A wheat-field near Rochester, in Kent, was found to be very 
slightly infested, having only one stem in many hundreds with 
pupa-cases upon it, so that it may be said that the actual 
damage was next to nothing. Also at Halstead, in Kent, 25 
miles distant from Rochester, the same degree of infestation 
was discovered upon wheat-plants, with no distinct damage. 
In several other parts of England and Scotland similar slight 
