PROPHYLAXIS OF MALARIA. 
65 
and top minnows especially being very active in devouring the larvae. 
W here there are small ponds or artificial collections of water of 
limited extent the stocking of them with these fish will often result 
in keeping them comparatively free from mosquito larvae, but the 
method, at best, is a very imperfect one, and possesses little of value 
for the military sanitarian, although, in very exceptional cases, it 
might yield good results. 
The abolition of breeding places in and about quarters and bar¬ 
racks. —It has already been stated that anopheline mosquitoes will 
breed in even the smallest collections of water and that, with several 
species, it makes no difference what the quality of the water may be. 
The old idea that the Anopheles will only breed in clean water and 
only in streams or larger collections of water has long ago been 
abandoned, and we now know that they will breed both within and 
without quarters and barracks wherever a collection of water forms 
large enough to contain the mosquito eggs. This renders the sani¬ 
tation of quarters and barracks of the very greatest importance in 
any campaign against malaria in a military post, and it is remark¬ 
able how many breeding places may be discovered around and in 
quarters and barracks that are believed to be perfectly free from 
them. Among the breeding places that occur in the quarters and 
barracks may be mentioned uncovered fire buckets, stopped drains, 
the unused hoppers in toilets, unscreened water tanks, earthenware 
vessels containing water, tubs, water traps that are not flushed out 
frequently, and the cans of water that are often used in the Tropics 
to place table legs in to prevent ants from getting to the food. All 
of these are favorite breeding places of certain species of Anopheles 
and are very frequently overlooked by those having little knowledge 
of the habits of these mosquitoes. 
If the post is in the neighborhood of native quarters, as generally 
happens in the Philippines and our other tropical possessions, the 
condition of these quarters as regards the breeding of mosquitoes be¬ 
comes of paramount importance and necessitates the greatest care in 
inspecting and abolishing the numerous breeding places that are 
always present around and in native houses. An inspection of the 
premises will generally reveal larvae in the water that has collected in 
broken bottles, old culinary utensils, tin cans, tin-lined boxes, water 
barrels, and chicken troughs. In addition, puddles of water will 
often be found teeming with larva in the immediate vicinity of the 
dwellings, and even the bamboo fence that surrounds so many native 
houses will be found to breed numberless mosquitoes in the cavities 
left by cutting off the bamboo near a joint or where the mosquitoes 
have gained entrance through holes made by boring insects. 
58000°—14 
5 
