92 PRACTICAL ZOOLOGY 



tried with this end in view; the one used most in this country 

 is a low grade of kerosene oil. An ounce of oil will spread over 

 about fifteen square feet of surface, and the film thus formed will 

 destroy all wigglers and many of the adults which come to drink 

 or lay eggs. Such a film will persist for about ten days. Oil 

 may be applied to small bodies of water with a watering pot and 

 to larger surfaces with a spray pump. 



Example of Mosquito Control. — As an example of the results 

 of work carried on in this way the antimalarial campaign waged 

 in Havana during the American occupation of 1901 to 1902 may 

 be cited. An Anopheles brigade of workmen was organized 

 under the sanitary officer, Doctor Gorgas, for work along the 

 small streams, irrigated gardens, and similar places in the sub- 

 urbs, and numbered from 50 to 300 men. No extensive drain- 

 age, such as would require engineering skill, was attempted, and 

 the natural streams and gutters were simply cleared of obstruc- 

 tions and grass, while superficial ditches were made through 

 the irrigated meadows. Among the suburban truck gardens 

 Anopheles bred everywhere, in the little puddles of water, cow 

 tracks, horse tracks, and similar depressions in grassy ground. 

 Little or no oil was used by the Anopheles brigade, since it was 

 found in practice a simple matter to drain these places. At the 

 end of the year it was very difficult to find water containing 

 mosquito larvae anywhere in the suburbs, and the effect upon 

 malarial statistics was striking. In 1900, the year before the 

 beginning of the mosquito work, there were 325 deaths from 

 malaria; in 1901, the first year of the mosquito work, 171 deaths; 

 in 1902, the second year of mosquito work, 77 deaths. Since 

 1902 there has been a gradual though slower decrease, as follows: 

 1903, 51; 1904, 44; 1905, 32; 1906, 26; 1907, 23. ' 



Driving Away Mosquitoes. — Mosquitoes not only carry the 

 germs of many diseases, but they are at all times disagreeable 

 companions, often rendering the most charming localities unin- 



1 Howard, L. O., Economic Losses to the People of the United Slates through Insects 

 that Carry Disease. 



