Larvicidal Fish.—The use of these has been strongly advocated in a
general circular and has proved successful in a number of cantonments. Re-
markable results have been obtained in quite a number of stations: Poona,
Lahore, Jullundur, Quetta, Jhelum, Lucknow, Ahmedabad, Hyderabad,.
Madras.
In this respect it is worth quoting from one experienced officer. "It
may be stated categorically that no collection of water which will house fish
should ever be oiled. Once they have been stocked with fish, these pools
need only the minimum of supervision and make invaluable traps which no
oiled pool is."
Gambusia (affinis Holbrookii) were used extensively in Kirkee and Poona.
A stock pond was maintained at the Cantonment hospital. From this the
Sholapur Road Quarry was stocked with 2,000 fish in 1939. Prior to this,
this quarry was a perpetual source of anophelene breeding and cost Rs. 500
per annum for pumping dry the worst places after the monsoon in order to
prevent further breeding. Since the addition of fish there has been no mos-
quito breeding and the ponds act as stock ponds for fish. The sisters' quarters
swimming bath has been similarly treated and many wells, tanks, ponds and
pools. All reports emphasise the value of these fish. They are hardy, breed
rapidly, stand transport and handling well, they are worthless for food and
difficult to catch without nets and so escape their cantonment enemies, in-
cluding children.
At Abbottabad Chilwa appeared to be better than Gambusia and at
Jhelum and other places Laubuca aptar (Ham) were found most effective.
At Mir Ali and at Khajuri Barbus (Puntius) Sophore (Hamilton) was used with
success.
In a recent conversation the Game Warden of the Punjab has made it
clear that there are two families of fish indigenous to the Punjab which are
good destroyers of mosquito larvæ; these are Tricogaster fasciatus and an
Ambesis, and the attention of anti-malarial officers is being drawn to these.
(ii) Destruction of mosquitoes.—Spraying.—This is now undoubtedly
proving its real value. Introduced by us in Northern Command in 1935 as
a universal method of defence against insect-borne infections, it is now in
demand by medical officers and laymen throughout all cantonments.
A circular was issued drawing attention to the advantages of spraying
in relation to other means stressing the fact that all insects are killed includ-
ing carriers of malaria, dengue, sandfly fever, tropical sore, and the dysentery--
diarrhœa group. Also the fact that this affords the one successful method of
cutting short an epidemic and that it is a method applicable to the spot in
which the troops are actually living.
All reports emphasise the value of pyrethrum sprays. Pyefly solution
has been the main standby, but Pyrocide 20 and Lethane have their advocates.
Unfortunately the cost of commercial Pyrethrum extracts is very high and in
many cases the money spent goes out of the Empire. Lethane is cheaper
and held by some to be more effective. During the year arrangements have
been in progress whereby we will buy our pyrethrum flowers direct from the
Empire source of Kenya and manufacture in our own Medical Stores Depart--
ment. These arrangements have now been completed for 1940. The culti-
vation of Pyrethrum in Kashmir and India is also under way.
Kenya flowers contain 1.4 per cent. or more of pyrethrins where as
Japanese flowers contain only 0 . 5—0 . 7 per cent. pyrethrins. Kashmir flowers
which have been examined are stated to contain 1.4 per cent.