84 
HOP. 
respectively on Hop and Damson or Sloe, in their conditions of young 
of two ages and of winged and wingless females. These were figured 
from life by myself; the reader will observe that the upper row was 
drawn from Hop Aphides, the lower from specimens taken from 
Damson or Sloe. 
Phorodon. 
Young. Winged females More advanced young. Wingless females. 
The upper row from Hop; the lower row from Damson or Sloe. 
The observations sent in and the specimens all appeared to point, 
as I then said, that there was good reason for believing “ That the great 
attack, which usually occurs in the form of Fly about the end of May, 
comes on the icing from Damson and Sloe as well as from Hop, and that 
the Hop Aphis and the Damson Hop Aphis are very slight varieties of one 
species, and so similar in habits as regards injury to Hop that for practical 
purposes they may be considered one." 
It is of very considerable importance to prove these points cer¬ 
tainly, as thus it is proved also that Hop-grounds near Plum and 
Damson orchards and Sloe-hedges are likely to be infested ; and also 
that where there is presence of these orchards, there washing betimes 
will prevent much attack going on to the neighbouring Hop-yards, and 
also that it would be very desirable to substitute some other plant 
than Sloe for hedges. 
The spring migration to the Hop appeared to be certain, but the 
autumn migration had not been so fully entered on ; and therefore the 
abstract of observation given below, partly taken in America and 
partly in this country, will be found to be of much value. 
In the American States the Hop suffers severely from Aphis, and 
consequently careful investigation of the above points have been made 
by Prof. Riley, Entomologist of the Department of Agriculture, 
U.S.A., and under liis direction for practical use. During his recent 
stay in England I had the advantage of personal communication 
with Prof. Riley on the subject, and he favoured me with a copy of his 
paper, read before our own British Association at Manchester, and 
