254 The Control of Mosquitoes 



The results of experimental tests with the three 

 substances, as obtained at Las Animas, were as 

 follows : 



Pyrethrum, btirned at the rate of one pound per 

 thousand cubic feet in layers not greater than one 

 inch in thickness, destroyed all mosquitoes in a 

 well sealed air-tight room within three hours. 



Tobacco, at the rate of two pounds of stems 

 (waste from Havana factories) per thousand cubic 

 feet, if it all burned, killed them in three hours. 



Sulphur, at the rate of one pound per thousand 

 cubic feet, was effective with an exposure of three 

 hours or less. 



It is almost impossible to find a satisfactory 

 grade of pyrethrum powder for fumigation pur- 

 poses on the market at the present time. 



In 1906 Kendall experimented with campho- 

 phenique as a ftmiigant; his methods and con- 

 clusions are quoted: 



This substance first used in the Gulf States, has 

 been tried with great success here. Berry, experi- 

 menting with this mixture, found that a shallow pan 

 placed upon a short piece of stove pipe formed a good 

 apparatus for volatilizing the campho-phenique, and 

 his method was tried here. The results were dis- 

 appointing, and except for a fortunate trial of the 

 fumes of this substance, they would have been dis- 

 continued. It was observed that the fvimes killed 



