1918. | BASHAMBAR Das: The Aphididae of Lahore. 207 
to twelve somewhat tuberculate sensoria on the 3rd article; cauda subequal or longer 
than cornicles; the thick smoky veins on the wings are distinctive. 
Life-history. —Sorghum in Lahore is sown about the latter. part of April, and one 
crop under a system of forced cultivation is ready in July. A second sowing is started 
about this time. The Aphid makes its appearance on a few low plants, near the 
margin of the field, early in July. Only small droves of them are visible after a good 
search. In August and September the attack is in full force. They decrease in 
numbers soon after this, and some of them shift to Panicum spp. ‘Till December 
the Aphid is in evidence on the latter host. The further life-history remains to be 
determined. 
Biology — This tiny insect possesses extraordinary powers of rapid multiplication. 
On seedling plants under glass chimneys the new-born young reached the reproduc- 
tive age after five days, and had moulted four times during this period. At first 
they bring forth from 3 to 4 young a day, but later the rate slowly decreases. 
The alate females quickly spread the species to neighbouring plants and frequently 
considerable portions of large fields are seriously attacked. Such an increase in num- 
bers is correlated with an equally excessive amount of excreta, the ‘‘ honey-dew”’ that 
is voided, falling in small drops over the lower leaves, dries up to a syrupy consis- 
tency and offers an excellent medium for the sooty fuagus Capnodium to grow on. 
Blackened and smothered leaves of Sorghum are unmistakable signs of the pre- 
sence of this A phis.. . 
These plant-lice are constantly attended by smaller as well as larger ants. 
Wasps and flies also hover round the plants. 
Enemies.—Besides the usual Coccinellids and a Lysiphlebus, there is a tiny Chalcid 
(Aphelinus sp.) that-does useful work in reducing its numbers. Aphids stung by 
Aphelinus turn jet black, but do not swell up and are easily recognisable ; the para- 
site on emergence either cuts a circular hole or ruptures the back. Its mode of 
attack is also unique... The female parasite at first flits from insect to insect examin- 
ing each with her quivering antennae. On finding one that has not already been 
stung she retreats a few millimetres, turns round facing away from the victim, and 
measuring her distance quickly darts out her long ovipositor and thrusts it into the 
abdomen and deposits an egg. The Aphis smarts for a moment and is quiet again. 
The parasite departs to repeat the process on another specimen. After the second 
day the Aphis changes in colour; at first it is greyish, then darker, and later jet » 
black. The insect adheres fast to the leaf before it dies. 
Pink variety.—A dark pink variety of Aphis sacchari also exists among the 
droves, or may be noticed feeding and breeding separately. Excepting in colour 
there is not the least structural difference between it and the almond-yellow form. 
A parallel case of this kind is known from Europe in Macrosiphum rosae, Linn. The 
two varieties have an entirely independent life; they breed perfectly true, and the 
progeny of one is never noticed to develop into adults of the other kind. 
The pink variety is never so numerous as the yellow, but in Lahore it is the first - 
to appear on Sorghum. 
