HOP APHIS. 
51 
and I could detect no difference in form between the lice from Hop- 
plants and those from Sloe or Damson. 
At the time of flight from the Sloes I figured the wingless females 
and pupas (or larvae containing young) from Hop-plants, and also from 
Damson or Sloe, and noticed a slightly greater amount of gibbousness 
in the root-joint of the antennae of the Hop Aphis, but, as shown vin 
the figures below, this difference was very slight. But, continuing 
3 4 
Advanced Stage (? Pup.®). Wingless Females. “ 
1, 2, Hop Aphis; 3, 4, Damson-Hop Aphis. 
the observations after a time, I found a difference in amount of 
development of these frontals in some of these young Hop-lice, and, 
on being furnished with a supply in Hop-cones, on the 26th August, 
I found that the frontal tubercles and amount of gibbous form of the 
root-joint of the horns was more developed ; in fact now (that is, in the 
summer form ) they precisely resembled the typical figure of the head 
Larvae of Hop Aphis. 
of the Humuli larva given by Mr. Buckton (fig. 1), which I copy for 
comparison with my own drawing (fig. 2, from a summer specimen). 
From the observations—though I submit my views with great 
deference—I incline to think that the difficulties as to increased 
summer development of the Damson-Hop Aphis have arisen from 
observers not studying sufficiently the parallel state of the Hop Aphis 
at the same time. 
Kaltenbach and Koch speak of it on Sloe in May and June; my 
own observations, both on Hop and on Sloe or Damson, began in 
March, and, according to what I consider the form then to be, the lice 
of both Humuli and Malalieb then are not furnished with as full develop¬ 
ment as in the warm weather. 
