1918.] BASHAMBAR Das: The Aphididae of Lahore. ~ 253 
tember so have nothing definite to say about this period. I believe that they do not 
produce sexual individuals that would lay eggs and probably hide themselves in shady 
places. Not only is the heat very trying, but the flow of sap also is very scanty 
in the plants during this interval. The insect is no doubt present in the hills of the 
Punjab as I have collected it in July and August around Simla. . 
As the plants resume activity in the autumn for secondary growth about Septem- 
ber, the plant-lice also become prominent. From September onwards through October 
and November wingless and winged females are produced in extremely large numbers. 
There is a preponderance of alate females and quite a large number of them as well as 
apterous females are pink-coloured. 
Experiments.—A series of experiments were started with one Aphid on each 
young pot-plant, covered over by a lamp chimney with a piece of muslin tied over the 
top. A circular piece of white or black paper was spread over the soil to find out the 
number of moults, the skin being cast down each time. 
The pot was kept in a dish in which water was poured 
as desired for irrigating the plant from below. The 
whole arrangement is shown in the accompanying 
illustration. 
The number of moults that each Aphid undergoes to 
reach the adult reproducing stage is four, and in pot 
plants they were spread over from 12 to 20 days. In . 
nature I believe the period is shorter. 
The apterous viviparous females under these condi- 
tions almost invariably gave birth to young ones which 
changed into alate viviparous females. The size of 
these laboratory specimens was usually smaller than 
those on the garden plants. Each individual lived up- 
wards of forty and even fifty days. They become very 
inactive after about the middle of November. 
Experiments were also arranged to find out when 
the true sexes were produced. Someof the pink pupae Te. aes dling a Celtis rene 
in December ultimately changed into small-sized males walis under a muslin-topped chim- 
with black antennae and conspicuous genital armature. en a dlıy 
ish of water and is irrigated from 
In the botanical gardens, under natural conditions, below. ‘This American device is 
they appeared in the second half of November, and Ve'y Satisfactory for studying the 
: life-history of plant-lice. 
were fairly abundant up to the middle of December. 
After this only a few isolated individuals were to be met with. At this time large 
numbers of apterous females turn red or scarlet and after December have their true 
characters well developed. They are the true oviparous females described above and 
chiefly cluster along the veins of leaves that are about to fall. In the last week of 
December and early in January there are large numbers of these oviparous females ; 
an occasional winged male and a few apterous and alate viviparous females are also 
present. 
