172 Memoirs of the Indian Museum. [Vor. VI, 
but in June this plant is entirely deserted and the Aphid either dies or migrates to — 
some unknown place. 
In this connection it is interesting to note that I have collected the identical 
species in Simla and the neighbouring hills in July and August. The hosts there are 
Cannabis indica, Cnicus sp. (a long-leaved and very spiny kind) and Artemesia sp. 
The life-cycle would, therefore, be completed somewhat as follows :— 
In March and April the eggs laid in the previous winter (December) hatch into 
stem-mothers, on some compositous weed and possibly also on Cannabis. They give 
birth to spring generations that stay in the plains up to about June. They arein evi- 
dence again during October and November. The hot summer months are in all likeli- 
hood passed in some cool shady places out of sight, or in the hills. 
Late spring individuals on Cannabis are smaller in size than the autumn ones. 
An Aphidius and a Lysiphlebus extensively parasitise this Aphid changing it into 
shining inflated skins with a circular hole on one side. The parasites are most 
abundant in April, issuing in large numbers from the bodies of wheat Aphids. 
The insect is apparently of no economic importance, unlike fie famous Hop- 
louse, Phorodon humuli, of Europe and America. 
Systematic. — The Cannabis Aphid is a near relation to the famous Hop-louse of 
Europe and America and is in some respects very similar to it, infesting a plant of the 
same order. But Hops (Humulus lupulus) are never grown here nor has Phorodon 
humuli, its pest, been so far observed in India. | 
The generic characters of Phorodon, Pass. (lit.=tooth carrier), as given by Pas- 
serini, loc. cit. and quoted below, are quite apparent. 
Antennae tuberculo frontali suffultae, articulo primo intus dente valido adaucto. 
Frons inter antennas plana; nectaria longissima, cylindrica vel leviter clavata ; caete- 
rum ut Siphononphora (Macrosiphum). 
The latest and emended characters given for this genus (van der Goot, Zur 
Systematik der Aphiden, 1913) are chiefly as set down by Passerini with additions, 
etc. as follows :— 
Body almost hairless or with extremely short hairs, not scattered in groups or 
knobbed. 
Lateral tubercles absent. 
Antennae not longer than body, in the apterous female distinctly shorter ; first 
segment with a strong tooth ontheinner side. Frontal tubercles well developed, hav- 
ing a similar tooth but more marked. The absence of sensoria on the third antennal 
article distinguishes it further from the genus Macrosiphum, which it resembles in 
other respects. 
The Indian species is rather peculiar in having capitate hairs scattered all over the 
body in rows, mostly directed backwards. The antennae and the characteristic teeth 
also carry a number of similar hairs. A slight clavation of the cornicles is also 
observable in the large apterous female. The pattern on the skin, 2.e. the peculiar 
corrugations described above, seems to be absent in all the species described so far. 
Both the capitate hairs and the skin-pattern are absent in the alate female. The 
