Mosquito Prophylaxis. 175 
and misery. Yet when we tackle the mosquito question seriously see how the 
picture changes ; we have only to look at such places as the West Coast 
of Africa, where the mortality has been reduced from over 500 per 1,000 to 
some where about 60, and Colon, formerly a death-trap, now almost a health 
resort in comparison. Even in the West Indies the mortality amongst troops 
was 69 per cent. in some cases until mosquito measures were undertaken. 
A Pian or Campalcn. 
Now let us turn to a plan of campaign against the mosquitoes. 
Personally I am convinced as the result of extensive and caerful house-to- 
house investigations, that most of the mosquitoes of Georgetown are bred in 
the houses and yards of the town itself. It is extremely difficult to find larvee 
in trenches and drains that are kept free from floating vegetation and stocked 
with fish. My colleague and myself have gone into this very thoroughly be- 
cause we so often hear the trenches and drain accused of breedings these 
pests. I can assure you that mosquitoes do not breed in trenches where 
there are fish and tadpoles, unless there is sufficient floating vegetation to give 
them shelter from their natural enemies, a matter that can be « easily remedied. 
But go into a yard and look for yourself into a wooden barrel or tub of stagnant 
water, and convince yourselves ; that is better than dozens of lectures. 
Now as to measures of prevention, which I will briefly classify as follows :-— 
Personal Measures :— 
Protection by means of nets. 
Systematic killing of adult mosquitoes. 
Rigid search for breeding-places on the premises 
Choice of clothes (white is preferable). 
Use of cheap culicides. 
Use of natural enemies. 
Quinine prophylaxis. 
General Measures :— 
Systematic inspection of likely breeding-places. 
Keeping of waterways free from vegetation and stocked with fish. 
Attention to drainage. 
Education. 
Penalties for harbouring larve and potential breeding-places. 
May I briefly review these measures. 
Nets are almost a necessity because they not only prevent fresh bites but 
pte vent carriage of infection by isolating the human reservoirs. Square nets 
are best and healthiest, and it is a good plan to keep these so folded during the 
day that mosquitoes cannot enter. The kind supplied locally and running on 
rings is excellent. Also it is a good plan to add a kind of vallance for about 
