DESTRUCTION OF MOSQUITOES 153 



exceptional. In England, so far as our experience 

 goes, the Anopheles larvae are usually met with in 

 shallow water easily heated by the sun's rays ; and 

 we have always found them in association with the 

 common green water-weed Spirogyra, though they are 

 not known to eat this. 



Attention to the standing water round houses or 

 near towns will do much to diminish the scourge of 

 mosquitoes. All pots and pans containing water 

 should be regularly turned out once a week, and 

 puddles should be brushed out. The larva takes 

 some seven days to develop, so that once a week 

 suffices to destroy each brood. All useless water 

 should be drained away and stagnant ponds filled up. 

 The introduction of fish has markedly diminished the 

 number of mosquitoes around the late Mr. Hanbury's 

 celebrated garden at La Mortela on the Riviera. They 

 eagerly devour the larvae, and should be made use of 

 in all large areas of water. For smaller areas some 

 ' culicide ' should be tried, and more experiments in 

 this direction are urgently needed. One of the 

 simplest remedies known is kerosene oil. A piece of 

 rag tied to a stick should be dipped into the oil, and 

 then applied to the surface of the water. The oil 

 diffuses in a fine film over the surface and clogs the 

 breathing tubes of the larval insect ; it possibly inter- 

 feres with the action of the surface tension — at any 

 rate, the larvae die. Fresh tar has the same eflfect. 

 This 'painting' of the water must be renewed once 

 a week. Wells and cisterns should be kept closed. 

 A more careful selection of the site for houses, arid a 

 more liberal use of wire-netting mosquito shutters, 

 will do much to minimize the risk to Europeans in 

 malarious districts. 



The various remedies suggested above have been 

 tried with success in different parts of the world. 

 The writer has been assured by an old inhabitant of 



