Rice Fields and Malaria. 281 
but it is not unusual, especially outside the estates, to find rice plots in the same 
field varying up to three or four months in growth, and some parts of the land 
in varying conditions from being submerged to quite dry. 
The anopheles require shade to breed in, I have seen pools teeming with 
mosquito larve in the open but no anopheles larve there, although anopheles 
were in the neighbourhood ; they also require more or less clean water and 
absence of fish, fish will soon eat up any mosquito larve they come across. 
When the rice is growing and the land is submerged fish are all about, and I 
have never been able to find larve among the growing rice in this condition. 
Some time back I was in a field which was covered with water and the rice 
nearly ready to cut, in this part of the field I could find no larve, but many 
small fish, [also came across no anopheles ; ina part of the field where the water 
was drying up preparatory to the rice cutting small pools had been left in the 
depressions, and from two or three of these pools among the growing rice I was 
able to collect anopheles larve (from which I developed later on an anopheles 
of the usual variety seen here, A. argyrotarsis or A. albitarsis), at this spot I also 
came across two or three adult anopheles ; in a couple of days these pools were 
dry so most of the larve did not develop, but a little rain falling would have kept 
up the pools so that the larvze would have reached maturity. We have in that 
field a natural exhibition of what occurs in the rice-fields generally ;—land sub- 
merged, fish present, no anopheles—land drying up, clear pools with shade, 
no fish, anopheles. We have therefore about the rice reaping time a great 
increase of anopheles bred under the favourable conditions above mentioned, 
and I need not point out that the absence of rains, heavy rains, irregular irriga- 
tion or drainage, or irregular level of land, will all make a difference in the 
formation of pools suitable for or against anopheles breeding, and so varying 
local circumstances and effects ; as for instance, land drying up with enough 
rain falling to keep up the pools but not to flood the land, would be the most 
suitable for anopheles breeding. Anopheles can also breed in the trenches 
connected with the rice-fields if these have much weeds and erowth, the fish 
prevent their multiplying much but a few of the larvee may escape to develop 
to maturity. I have found a stray anopheles larva with other mosquito larve 
in such trenches ; the trench on one side of my field is connected with the rice- 
fields which surround it on two sides, at the early part of the year I had the 
trench weeded and all rushes cut down, and whereas previously I could neaaly 
always find anopheles in the house, since then they have been distinctly rare. 
It may be thought that, as the water drains off, enough fish would be left in 
the pools to destroy the larve, but this is not so ; when the water is going off the 
fish go with it mostly, they leave these small holes but may remain in the 
larger ponds and depressions. 
The question now arises, Do the people living among the rice-fields suffer 
more from malaria than elsewhere ? This is undoubtedly so. On one estate 
the excessive number of people affected with malaria which come from a settle- 
ment among rice-fields, has been known to us for years ; on another estate co- 
incident with a new settlement among new rice-fields, there was a V ery markedly 
large number of malarial cases from the settlement, and each year shows it. 
