WHEN TO BEGIN THE WORK AND WHEN 

 TO CLOSE 



The best results are secured in a new district by 

 eliminating as far as possible the last brood of mos- 

 quitoes in the autumn, i.e. oil or drain off all mosquito 

 breeding pools in October and go over the territory 

 once again in November. In this way the number of 

 mosquitoes which hibernate over winter is reduced to 

 a minimum. The spring work should begin in March, 

 depending on the weather, --if warm, the work must 

 begin earlier in the month ; if cool, then later. This 

 can only be ascertained by inspecting likely pools in 

 order to determine whether mosquito larvae are present 

 and what size they have attained. Usually the last 

 larvae are found in October and the campaign may 

 usually close safely with the end of this month. This 

 applies only to the Anopheles mosquito (the malaria 

 bearers) and does not apply to the Culicine varieties, 

 including salt marsh species. 



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