694 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol, XII, 
why it suits them, As far as my experience goes, you will never find them 
in tubs, flower-pots, buckets, or cisterns, where you will find larve of Culex 
in hundreds. Nor will you find them often in tanks, wells, or any deep 
water ; nor in brown, muddy puddles; but in shallow, clear, or greenish 
pools, fed by running water, you will rarely miss them, I am inclined to 
think that they cannot live in absolutely stagnant water. It was a surprise 
to me to find them in the Frere and Wellington Fountains, but I think the 
explanation is that the water in these was always leaking away more 
or less and being renewed, either by showers of rain, or when the fountain 
was allowed to play, as it was occasionally, Since the fountains were 
repaired and kept full the larve have certainly diminished, But the only 
way of getting to a clear understanding of the conditions which any 
animal requires is to learn its habits; and the peculiar habits of the larva 
of Anopheles throw some light on the question before us, Its food is both 
vegetable and animal, The favourite vegetable food isa soft Fucus, very 
like cotton-wool dyed green, which is found in clear running water; or 
that thick, spongy growth which clothes the sides of fountains in which 
there are no fishes, and gets detached and floats like a thick, dark green 
scum. ‘The principal animal food is the cast-off skins and pupa-cases of 
water larve, including those of its own kind, and the remains of dead 
mosquitoes and other small insects, These often collect in patches on the 
surface of a pond, and one dip under such a patch will secure hundreds of 
larve after you have searched the rest of the pond ip vain, Now the larva 
of Anopheles, unlike that of Culex, floats flat on the surface of the water, 
and it is much more unwilling to go down than Culex. If green food is 
to be had not more than two or three inches deep, it will go down and 
feed, but it comes up again very soon, and would evidently rather not go 
down at all, As it floats you will see two little organs on the front of its 
head incessantly stirring the water, These are the “ whorl-organs,’ They 
are crowned with little brushes of bristles, and their function is to keep up 
an eddy, by which every little floating particle which passes by is sucked 
in towards the insect’s mouth, With a lens you can see this quite plainly 
and observe ii seizing the little particles with its jaws, sometime eating 
them and sometimes throwing them away with an angry toss of its head. 
I do not think that even living objects, if small enough, are refused, and, 
in fact, I am almost sure that the larger larvee sometimes eat the little 
ones, They are all very ill-natured and bite savagely at each other when 
they get the chance. This way of feeding explains why Anopheles likes a 
certain amount of motion in the water, for it brings food, and why it must 
starve in deep water unless there chances to be a great deal of food, 
animal or vegetable, floating on the surface, The larve of Culex dive 
much more freely and are more promiscuous in their diet, and, since they 
float with their heads down, they do not care much for floating matter, 
ee 
1 ia te! Ni eo ee 
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