Extermination and Prevention of Mosquitoes .—Mosquitoes require for their development standing water. They cannot arise in any other way. A single crop soon dies and disappears unless the females find water on which their eggs may be laid. In order to prevent mosquitoes, therefore, the requirement is simple.
No Standing Water.—Pools of rain water, duck ponds, ice ponds, and temporary accumulations due to building; marshes, both of salt and fresh water, and road-side drains; pots, kettles, tubs, springs, barrels of water, and other back-yard collections, should be drained, filled with earth, or emptied.
Running streams should have their margins carefully cleaned and covered with gravel to prevent weeds and grass at the water's edge.
Lily ponds and fountain pools should, if possible, be abolished; if not, the margins should be cemented or carefully graveled, a good stock of minnows put in the water, and green slime (Algæ) regularly cleaned out, as it collects.
Where tanks, cisterns, wells or springs are necessary to supply water, the openings to them should be closely covered with wire gauze (galvanized to prevent rusting), not the smallest aperture being left.
When neither drainage nor covering is practicable, the surface of the standing water should be covered with a film of light fuel oil (or kerosene) which chokes and kills the larvæ. The oil may be poured on from a can or from a sprinkler. It will spread itself. One ounce of oil is sufficient to cover 15 square feet of water. The oil should be renewed once a week during warm weather.
Particular attention should be paid to cess-pools. These pools when uncovered breed mosquitoes in vast numbers; if not tightly closed by a cemented top or by wire-gauze, they should be treated once a week with an excess of kerosene or light fuel oil.
Certain simple precautions suffice to protect persons living in malarial districts from infection:
First: Proper screening of the house to prevent the entrance of the mosquitoes (after careful search for and destruction of all those already present in the house), and screening of the bed at night. The chief danger of infection is at night (the Anopheles bite mostly at this time).
Second: The screening of persons in malarial districts who are suffering from malarial fever, so that mosquitoes may not bite them and thus become infected.