258 BACOr : MOSQUITOES AND THE DANGER OF MALARIA. 
no record of the intensity of the mosquito population when 
Ague was prevalent. In the future, however, it may enable us 
to state that there is no danger of Malaria, even in districts 
where Anopheles mosquitoes are present, unless their numbers 
reach a certain level. 
V.—The Breeding Places of Mosquitoes. 
As already pointed out, there is a broad general divergence 
between the places most suitable for Anopheles mosquitoes and 
those of other groups. The former, as typified by A. 
maculipennis, keep more to open sunlit water than do 
the majority of the non-Anophelene species. An important 
fact to remember in either case is that small, impermanent, 
and very shallow collections of water, or waters which are much 
obstructed or clogged with weeds, require much more careful 
attention as breeding places than do larger, freer, and more 
permanent pools or streams. The reason for this is that the 
latter are tenanted by enemies ot the mosquito larvae, which 
are usually few or wanting in the small, impermanent, or shallow 
waters. It is true that we find A. maculipennis in rivers and 
permanent ponds, though as a rule Culicinae larvae are very 
•scarce in such waters ; but the chances of their survival to the 
adult stage are small in comparison with those present in grass- 
grown ditches, running swamps, or the hoof-holes of cattle 
on the soft margin of a pond or stream. Of course, they are 
more easily seen in open water, and the larger collections of 
water are more easily found and charted, but they are less 
dangerous. 
This will be at once apparent if we consider the natural 
enemies of the mosquito, which are many. In the air, bats, 
birds, dragon flies, wasps, and predaceous dipterous flies, all 
take a very heavy toll of the adults when upon the wing ; while, 
when at rest, not only do some of these still persist in their 
attacks, but numerous other animals join in. Lizards, toads, 
and frogs snap them up ; ants, spiders, and (abroad) scorpions 
prey upon them, both in and out of doors. Ants, by reason 
of their omnipresence, are, in the tropics, very formidable com¬ 
petitors of the spiders ; which in temperate climes are probably 
the chief foes of resting mosquitoes. The dangers amid which 
the adult mosquito is forced to rest are instanced by the continual 
