92 
Proceedings of the Boyal Society of Edinburgh. [Sess. 
in England, and by E. M. Patch in America, bat until recently the fate 
of the aphis in the late summer has been a mystery. It was well known 
that this species appeared on the currant as the stem mother at the end 
of March or beginning of April, and reached its maximum abundance in 
June. During July it became scarcer, the red blisters were emptied, and 
in August it vanished altogether except for an occasional apterous female. 
It was an open question whether these remaining females were able to 
maintain the race until the autumn, when they gave birth to the winged 
males and wingless females, which, after copulation, produced the winter 
eggs ; or whether there was an emigration to a second host plant in June, 
followed by a return migration in autumn of males and gynuparse, such 
as Borner (1) has shown for Bhopalosiphum ribis. 
On June 21st, in a cornfield near Cambridge, I found a plant of 
Galeopsis tetrahit infested with the apterous forms and nymphs of a species 
first described by Kaltenbach as Aphis galeopsidis, and later by Passerini 
and Buckton as Phorodon galeopsidis. In spite of their greater size, I 
was struck at once by their resemblance to M. ribis, and this impression 
was confirmed a few days later when the winged females appeared. 
I took six apterous, and two alate, females of M. ribis from the genera- 
tion series (A. I, 7) and transferred them to a potted plant of Galeopsis A 
In two or three hours they had all settled down to feed, and by the next 
morning were producing young freely. Both P. galeopsidis and the 
transferred M. ribis attach themselves closely to the under side of the 
leaves, which when young have a tendency to curl round the aphides 
in the axis of the mid-rib. I continued to rear this stock of transferred 
M. ribis throughout the summer. During drought, when it became 
difficult to obtain fresh plants of Galeopsis, I substituted Lamium 
purpureum with complete success, but the aphides died within twenty- 
four hours when placed on such aromatic Labiatse as Mentha or Nepeta. 
About the same time, I collected plants of Galeopsis infested with P. 
galeopsidis in two other places near Cambridge, and likewise found this 
species on Lamium purpurem and Lamium amplexicaule. Early in July 
I observed the apterous forms swarming under the leaves of Veronica 
* At this time I was not aware of the experiments of Gillette and Bragg {Jour. Econ. 
Ent ., Concord, vol. x, 1917, p. 388), who successfully transferred examples of M. ribis 
from Ribes to Stachys and Leonurus , and autumn forms back from these plants to currant. 
The writers suggest that Kaltenbach and Koch may have had this species under observation 
as galeopsidis, but do not discuss the discrepancies in the description of the two forms by 
the first-named observer. Kaltenbach {Die Pflanzenfeinde , p. 484) gives Aphis lamii , Koch, 
as a possible synonym of his own galeopsidis ; but Koch cannot have referred to this species, 
since he describes his lamii with dark cornicles. 
