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CHAPTER IV.
THE MOSQUITOES OF KARACHI-contined.
Section 1.
The Mosquitoes of Karachi.-The Culicid Fauna of Karachi is very limited.
The different species met with are:-
Culicines.
Stegomyiata Fasciata Culex Fatigans Culex Concolor Culex Taeniorhynchus Theobaldia Spathiapalpis.
Anophelines. Nyssomyzomyia Rossi Neocellia Stephensi Cellia Pulcherima.
By far the commonest is Culex Fatigans and was found everywhere. The S. Fasciata came in next in extent of distribution, and each of these were severally proportionate to the permanent and temporary breeding places of the locality respectively.
Stegomyia Fasciata.
Section 2.
1.    The genus Stegomyia is characterised by the head  and scuttellum
being entirely clothed with flat scales.    S. Fasciata is the only species found in Karachi.    It is essentially a
domestic mosquito living and breeding in the immediate neighbourhood of houses. It adapts itself readily to all sorts of conditions, provided the water is stagnant. It is pre-eminently a chatty breeding mosquito here, even clean and new chatties with clean water being sometimes found full of them. It cannot possibly be the odour of baked moist earth that attracts them most, because in Kumbarwadda, i.e., the potter's quarter, where chatties are baked or made, their larval and adult population differed in no respect from any other similar quarter, and perhaps it was less still. It does not breed by preference in dirty or foul water, but can adapt itself readily under necessity to all sorts and conditions of life, e.g., wells, garden tanks, tubs smeared with coal tar, cess-pits, etc. Their presence in cess-pits can only be accounted for by their being transferred from an original receptacle, as when this cess-pit water was bottled, they died either from development of foul gases or a thick film of fungus on surface of water.
2. Larvae.-The larvae are somewhat elongate with rudimentary antennae and a short stout syphon. They are of a creamy white colour and darken later to a pale brown tinge, when they are about to change into pupae. The intestinal canal can always be made out by the naked eye as a dark line in the body. Their movements are sluggish and wriggling, and they pass a greater part of their time in browsing at the bottom. At the surface they hang limp down almost vertical, or go round and round the receptacle by wormlike movements. The size of the larva differs according to the quantity and nature of food available, and the greater of it there was, they became plump and opaque white, suggesting almost a fungus growth on their body. I am inclined to believe that they live entirely on dead organic matter-vegetable or animal-and were never observed to touch unicellular living organisms running even near their mouth-brushes. Active Vorticella were often seen living and attached to a part of their body. No definite period can be assigned to the length of their larval life. In the Laboratory when abundant food was supplied they turned into Nymphae on the 9th day at the earliest (from the time of the hatching of eggs) to the 15th. They were observed to moult twice. Under conditions found outside, the shortest time has been two weeks and the longest nine weeks; and that, while some of the same breed, attained maturity earlier, that of others was considerably retarded. Another thing noticed was that the size of the larva in no way limited that of the adult Imago-small mosquitoes hatching out of even big larvae and vice versa.