hop aphis. 
49 
place where it was born ;* but just taking one or two special examples 
of migration from one kind or one species of plant to another, we have 
the common Bean Aphis or Collier (Aphis rumicis, Fab.), which 
often hybernates (and sometimes lays its eggs) on the Common Furze, 
and thus affects this plant both before and after the growth of its 
better-known food, the Field Bean. 
As an example of migration to and fro on the wing from one species 
of plant to another, we have the Oak Aphis, Phylloxera Quercus 
(Fonscolombe), which is stated commonly to deposit its eggs in the 
bark of the Chermes Oak; in due course winged females appear 
about the end of May, and are stated all to migrate to the Hairy Oak, 
Quercus pubescens, whence further generations were seen, by M. Lichten¬ 
stein, to return to the Chermes Oaks in August.! 
With regard to evidence of the migration of Hop Aphis (whether 
we call it the species Humuli or the variety Malaheb) from Plum to 
Hop, we have the direct statement of several competent entomologists 
to the effect of their knowledge of this taking place. 
* 
The German writer, C. L. Koch, in his well-known work on 
Aphides, states that in the last days of the month of May the Hop 
Aphis (Aphis Humuli , Schrankj are to be found in large companies on 
the young shoots, and on the under side of the leaves of Plum and 
Sloe. In these companies the writer observes that only one mother 
Aphis was found : all the descendants present were either already winged 
individuals or larvce of the same. Not one example of the larva of a wing¬ 
less specimen was to be found there. 
After details of description the writer continues :—In the month of 
June these plant-lice forsake the leaves of the Sloes and betake themselves to 
the wild and field Hops, where they often cover the under side of the leaves 
with their vast numbers, j 
With regard to this same Hop Aphis, it is stated by J. H. Kalten- 
bach, in his exhaustive work on insect plant-pests,§ that the Aphis 
Humuli (Schrank) often lives from July to September under the leaves 
and on the upper part of the stems of the Hops in numerous com¬ 
panies, and that he had found it also as early as May on the Sloes. 
Francis Walker, a well-known English entomologist, mentions that 
this same Hop Aphis develops on Sloes, and the second generation 
migrates from thence to the Hops, but returns again later on to 
the Sloes. || 
Further, we have the opinion of Mr. Gr. B. Buckton, which is of 
* Letter from M. Jules Lichtenstein to G. B. Buckton, F.R.S., ‘Brit. Aphides,’ 
vol. iv., p. 65. 
f ‘Brit. Aphides,’ vol. iv., pp. 49, 50. 
\ ‘ Die Pflanzenlause-Aphiden,’ von C. L. Koch, p. 115. 
§ ‘Die Pflanzenfeinde aus der Klasse der Insekten,’ pp. 176 and 534. 
|| ‘ Ann. of Nat. Hist.’ xx., p. 209. 
E 
