224 MOSQUITO ERADICATION 



7. Make use of some mosquito-repelling substance in the home. 



8. Kill all mosquitoes that succeed in penetrating the screens 

 or otherwise entering the house. 



9. If symptoms of malaria develop, use quinine, as directed in 

 a previous chapter. 



THE RICE-FIELD PROBLEM 



An area within or near a rice-field is the worst possible site for 

 a home from an anti-mosquito point of view. 



In the light of our present knowledge, there is no really effec- 

 tive means of protection in such a case. This is due to the 

 methods used in growing rice, which call for flooding of the culti- 

 vated area for several months. In the Arkansas rice section, 

 flooding water is first applied when the rice is 3 to 5 inches high; 

 the depth is increased with the growth of the rice until a depth 

 of 4 to 6 inches is reached, and this depth is maintained during 

 the growing season. It will be seen therefore, that rice-fields 

 constitute an ideal breeding-place, since there is quiescent water 

 and dense vegetation. 



Some slight measure of success in reducing larvae by means of 

 Gambusia affinis is reported by Tarbett. 1 He states, however, 

 that they fail generally to penetrate the rice, remaining chiefly 

 in the more open water along the levees. 



Tarbett 1 also reports that broad-casting oil-soaked saw-dust 

 appeared to give somewhat encouraging results. Dry red-oak 

 saw-dust was used. Thirty gallons of oil, soaked up into 10 

 bushels of saw-dust, sufficed for one acre. "The results obtained 

 were encouraging," he says, "breeding being controlled for a 

 period of two weeks after application, and this without an appre- 

 ciable effect upon the rice. In this experiment, fuel oil appeared 

 to give better results than did mixed oil" (mixed with kerosene). 



THE RICE-FIELD PROBLEM ABROAD 



According to Gunasekara, 2 little rice is raised in Ceylon because 

 of the increased incidence of malaria which it gives rise to and of 

 the vigorous methods of combatting the infection carried out 

 there. These include: abandonment or removal of all dwelling- 

 places within a mile of the rice-fields; destruction of all harboring 



1 Transactions of the First Annual Conference of Sanitary Engineers, 

 U. S. Public Health Service, 1919. 



- Journal, Ceylon Branch, British Medical Association, 1919. 



