1918. | BASHAMBAR Das: The Aphididae of Lahore. 149 
somewhat protected inside muslin bags, ripened in some cases as late as the middle of 
December, but the majority of the galls are quite empty long before this time. Occa- 
sionally some yellow apterous viviparous females are also seen reproducing at the 
time, but the last generation all change into pupae and ultimately fly out, the 
apterous females dying a natural death. 
These winged females are very impatient to discharge their load of young and 
even on a slide they would expel a few of them by strong peristaltic movements of 
the abdomen. Inside the muslin bags the tiny young crawl about for a day or two, 
and may even moult once, but they soon die, as they absolutely refuse to take 
nourishment either from the gall or from the Pistacia leaves. Evidently it is some 
other plant to which the winged females migrate and on which the young can thrive. 
During the little spare time I had outside official duties, I made several attempts to 
determine this alternate host. It is recorded of the European species of Pemphigus 
(on Pistacia) that they spend a part of their life history on graminous plants. Taking 
a hint from this, several grasses and similar weeds were enclosed in cages containing 
alate migrants issuing from galls, but in no case was the artificial colonisation suc- 
cessful, and the young plant-lice died after their first moult. 
From certain anatomical resemblances it was strongly suspected that the insect 
provisionally described below as Pemph. cynodonti, n. sp. may be the alternate form. 
Its time of appearance in early October more or less coincided with the ripening of 
the galls. But as colonising experiments gave negative evidence no definite proof 
can be adduced to maintain this hypothesis. It may be expected that with increased 
vigilance and better opportunities for conducting field and indoor observations the 
alternate host of this important insect will soon be ascertained. Till then our 
knowledge of its life-history must remain incomplete. As at present known it is as 
follows :— ; 
Life-cycle.—The. foliage buds of Pistacia open about the latter half of February, 
some fifteen days after those that contain shoots of inflorescene. Almost simultaneous 
with the appearance of the tender pinkish leaves tiny protuberances—the future galls 
—are visible at the bases of the leaflets. These all enclose one darkish aphid each, 
hatched from the egg, laid some time previously upon the bud. As the leaves mature 
the galls grow and the aphids within (stem-mothers) multiply ; yellow apterous females 
are born that reproduce again parthenogentically. This continues from March to 
October when the galls ripen and the last generation of plant-lice change into pupae, 
ultimately becoming the winged insect in November which migrate to some other 
plant. 
The points requiring elucidation are :— 
(a) What is the plant or plants to which the insects go. 
(0) When are the sexuales developed. 
(c) What time do the ‘‘ return migrants ’’ come back to Pistacia. 
It must be these latter that deposit the eggs, which hatch out again in early 
March to start fresh colonies in the galls. 
Possible connection with Pemphigus cynodonti.—From Pemphigus cynodonti, n. sp. 
