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General effect of anti-larval operations.-Whilst in special circum-
stances it may be desirable to treat by drainage, training of streams, or
petrolage, some large source of anopheles within a quarter or half a mile
of a bungalow or coolie lines, we do not believe that any general attempt
to reduce malaria in the Duars by anti-larval operations would have the
slightest effect. The conditions met with offer very great difficulties.
The area involved on even the smallest gardens, the changing na-
ture of the breeding places, the torrential character of the streams and
the jungly conditions of many portions of the country have to be con-
sidered. It must be rememberd also that labour is everywhere at a pre-
mium at the very time when such measures would require to be carried
out on a large scale, and there is little doubt that were the tea gardens
to undertake, however energetically, anti-malarial operations on these
lines the scheme would result in failure and disappointment. The crux
of the whole matter lies not in the question as to whether anti-larval
measures could, or could not, be made effective (for the treatment of
any breeding place can be ensured by sufficient expenditure and atten-
tion), but in the impossibility of carrying out such measures in the
Duars under the most hopeful conditions as regards money and labour
that is ever likely to be available for this purpose.
It would be no advantage to the tea community to demonstrate
experimentally that malaria could be combated by such means in some
particular spot. The tea industry is concerned, not in the improve-
ment of one particular garden, but in the bringing about of a better con-
dition throughout a wide district; and if by concentrating its energies
on a single garden it were to produce effects, the problem of malaria
in the Duars would still be untouched, for it is certain that they
could not extend operations of the necessary thoroughness generally
through the district. The sources of anopheles in the Duars would
be very difficult to control, and the effect of only partial measures
would be unimportant, for in districts of this nature nothing
short of absolute extinction would appear to offer much hope of
reducing malaria by measures directed against anopheles. Fortu-
nately perhaps no attempt on a large scale involving great expenditure
has been made on these lines in the Duars.