CORN APHIS OR PLANT LOUSE. 



43 



seen that Mr. Bishop alkides to the browu fly being more numerous 

 than the green kind, and also that the infestation was chiefly in the 

 most backward ears : — 



" The Grain Fly. — For many years I have carefully watched the 

 Wheat crop at this important period, but yesterday (July 21st) I 

 discovered what I have never noticed before, namely, large numbers of 

 the green fly which usually attacks Eoses, and still larger numbers of 

 a brownish fly somewhat similar, but rather larger, which I found in 

 between the meshes of the Wheat ear. I find the same thing more or 

 less in all my Wheat fields, but chiefly in most backward ears, where 

 the Wheat has tilthed. I should be glad to know if any of your corre- 

 spondents have noticed anything of the kind, and what effect it is 

 likely to have on the yield ? Certainly not a good one." — (E. J. B.) 



To this I forwarded the following reply : — The insects observed by 

 your correspondent as infesting his Wheat, and of which you send me 

 specimens, are the "Grain Aphis," sometimes known as the "Dol- 

 phin," or " Plant Louse." The green kind is Siphonophora (ApJiis) 

 gran aria ; the brown kind has been named Aphis aveme, or "Oat 

 Aphis," but it is very doubtful whether it is not only a variety of the 

 Wheat Aphis. The infestation is rather prevalent this year. The 

 Aphides do mischief by piercing into the tender parts of the ear with 

 their suckers, and withdrawing the juices, and they cause injury at the 

 same time, by the innumerable small punctures of their suckers into 

 the tender tissues. They multiply with very great rapidity, and 

 (excepting in the full-grown Aphides, being in some conditions fur- 

 nished with wings) they are nearly alike in all their stages. 



The amount of damage depends on the number of the Aphides 

 present, or the stage at which the ear is attacked. Sometimes the ear 

 is almost black with them ; but, generally, if attack does not come in 

 great quantity until the ear is just turning, little harm is done. Then 

 the tissues harden so rapidly that the Aphis, or "Plant Louse," cannot 

 drive its sucker in, and so does no harm. 



The only year in which I have had notes of this attack being 

 remarkably prevalent was in 1885, when I had reports of presence 

 from various localities — from Fife, in Scotland, down to Kent, but 

 chiefly from the district across England, from Cheshire to Lincoln- 

 shire. 



Various kinds of dressings have been suggested as being possibly of 

 service, and in the early stage, whilst the plant lice are still only on 

 the leaves, they might perhaps be of use. But when the Wheat ears 

 are formed, and infested, I should greatly fear, myself, that any 

 attempt to apply insecticides would only risk farther loss by injury in 

 passing amongst the plants, and be of no practical service." — E. A. 0. 



Specimens of Wheat ears severely infested by Aphides, mostly 



