10 
HOP APHIS. 
Bean crop for a long time in a field, yet that from some neighbouring 
shelter or other there come the females which produce the Colliers ; 
and so it appears with Hops. In the case of the Bean Aphis (for one 
place) they shelter in Gorse ; and if either with Bean or Hop we could 
find where the shelter commonly is, then we could go forward. 
The preceding observations give (as far as I can give it at present) 
the state of the case as regards first appearance of Aphis. As far 
as these observations go, it appears that the attack is certainly first 
observed on the upper part of the plant , and in the form of Fly ; and 
that we ha ve no evidence from the most careful search that the eggs or 
the Aphides are to be found in autumn, winter, or spring, anywhere 
about Hop-rubbish or in the earth. 
But nevertheless I do not think the point is proved yet, for this 
reason:—I am aware, though the notes have not been sent in this 
year, that there have been a few observations of Lice being first seen. 
I noticed that amongst my own Hops, the only plants which escaped 
attack were a set or two which I had examined so carefully for Louse 
and egg presence that hardly any earth or shelter remained. Also, 
though I failed to capture it, I have seen what appeared to me to be 
the wingless female early in the season on the lowest leaves of a Hop 
yearly infested in my own garden. Also, though I have not wished to 
introduce exceptional conditions into this paper, I have a note taken 
after careful examination by Mr. C. Whitehead, in which he informs 
me that in a Hop plant which he was growing in a greenhouse the first 
appearance was certainly of ‘ Lice.’ 
This is an important observation, and so is the following :— 
Isolation of Hop. 
“ In answer to your letter respecting the experiment on the Hop 
covered with muslin, I had the plant covered up early in the season 
(about the end of May), first of all seeing that the plant was thoroughly 
clean. I used three poles about nine feet high, placing them tri¬ 
angularly round the plant (the three poles meeting in a point above it). 
I then tacked the muslin securely to the poles from the bottom to the 
top, allowing six inches of muslin to be buried in the soil at the bottom 
to make sure that nothing could get in, except they came directly from 
the soil. It was simply impossible for anything to get in from the 
outside, the muslin I used being very fine. The plant continued clean, 
as I informed you in writing to you once or twice afterwards [it was 
mentioned up to June 15th as being ‘ perfectly clean,’ Ed.] On 
examining the plant again I found that there were a good many Fly on 
the leaves, and also a quantity of wingless Aphides ; and later on 
(on August 9th) these plants that were covered with muslin were 
