Flight and Attraction of Mosquitoes 1 13 



successful that other methods of collecting were 

 abandoned. 



When the first net was installed the biting was so 

 continuous that after it became well filled with 

 mosquitoes the observers crawled out from under 

 and tied up the bottom of the net. Conditions 

 were becoming unbearable even to those persons 

 who were accustomed to be bitten frequently. 

 Next morning soon after daylight nearly all the 

 mosquitoes within the bar were dead, apparently 

 killed by the drying action of the wind during the 

 night. After this experience, as soon as a sufficient 

 quantity of mosquitoes collected in the upper parts 

 of the mosquito bars, they were sprayed very 

 lightly with aqueous solution of aniline dye and 

 liberated by turning the mosquito bar inside out. 

 This operation was repeated as long as the obser- 

 vers could keep their tempers, and then a general 

 retreat was made to the other side of the canal 

 where there were no mosquitoes. 



Very patient negroes were necessary to act as 

 bait under the mosquito bars! Had the boat 

 used for crossing the canal been conveniently near 

 the bait might have escaped. Many of the stained 

 mosquitoes were recovered, and even two weeks 

 after the last catch was stained, some of them were 

 captured near the place where the nets had been. 



