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" (o) Wells may be protected from mosquitoes in many ways :—
" (1) They can be filled up and permanently closed.
" (2) If the well is required as a water supply a tube-pump*
" (Abyssinian Tube) may be placed in the well, which can then be filled
" up with gravel and sand as recommended by Koch.
" (3) Wells can be completely covered with stone or brick-work,
" reinforced concrete, sheet iron or wood, with no opening, and if
" necessary a pump can be used for drawing water.
" (4) Wells may be protected by a cover of stone-work or concrete,
" sheet iron, wire gauze or wood, fitted with a trap-door and stocked
" with suitable fish.
" (5) In some cases wells stocked with large numbers of small fish,
" of a species known to pray upon mosquito larvae, require no other
" measure of protection if they are kept free of weed and floating matter.
"Wells in which water has becorn8 obviously foul, putrid and
" stinking are no danger from the point of view of malaria, because the
" mosquitoes that carry the disease will not breed in putrid water. On the
"other hand, these wells often breed enormous number of other mosquitoes.
" Wells which become foul either from non-use or from the entrance of
"sewage of foul matter should be filled-in or permanently closed.
"(p) With a view to prevent malaria, owners of wells should there-
" fore be obliged to register them and adopt one of the following
" alternatives:—
" (1) Fill up the well.
"(2) Permanently cover the well with concrete, stone or brick -
" work or sheet iron, allowing no opening through which a mosquito can
" pass, and providing no trap-door, but fixing a pump in position if the
" water is required for use.
" (q) Or, if unwilling to protect them in this manner, owners of walls
" of type A or B should be required to—
" (3) (a) take out a license for their wells;
" (b) protect it with a well-fitting cover of iron gauze (of not
more than 1-16th inch mesh) or sound wooden planking
or sheet iron, with or without an accurately fitting trap-
door ; and in addition
" (c) keep the well stocked with a sufficient number of small
fish of a species known to destroy mosquito larvae;
" (d) allow the well to be inspected periodically :
" Provided that, in the case of wells of type B situated not less
" than 50 feet from a dwelling-house, owners may be allowed to
" (4) (a) take out a license for the well;
" (5) keep the well stocked with large numbers of suitable fish;
" (c) keep the well free from weed and floating matter;
" (d) allow the well to be inspected periodically.
" Wells required for religious purposes should be covered either with
" wire gauze or plate glass to allow of sunlight penetrating to them, but
"they must be liable to inspection, and if necessary be stocked with
" fish. [Foul wells should not be licensed, but the owners should be
" compelled to close them up.
" (r) Large Tanks.—All large tanks should be licensed. They should
" be kept free of weed other than Wolffia arhiza, and be stocked with
" large numbers of fish, or failing this periodically treated with kerosine oil
" in amount proportionate to their area. Tanks which continued to
* The cost of an Abyssinian tube and pump is only about Rs. 25.