Airplane Dusting in Control of Malaria Mosquitoes 13 

 AN ADDITIONAL CHECK ON THE RESULTS 



As an additional check on the results of the poisoning in the two 

 completed experiments porcelain pans 11 inches in diameter and 

 containing 10 larvae each were placed at the different stations before 

 the dust was applied and were examined the following day for the 

 percentage killed. (Fig. 8.) On Ex Via Lake all the larvae were 

 dead in seven out of nine pans, whereas, in the other two pans, 5 

 larvae remained alive in one and 2 in the other. The first of these 

 was in a pocket along the shore, and this was the only part of the 

 area where any considerable number of larvae were found remaining 

 after the treatment. A few small larvae were found at several of the 



Fig. 8. — One of the pans containing larvae and floating on the surface of the water 

 as used in the lake-dusting experiments in 1924. The view also shows the water 

 conditions encountered during these tests 



other stations and the total reduction for the whole area was 88 per 

 cent. 



At the second lake the treatment was highly successful, as all of 

 the larvae in the 11 pans were killed and none were to be found in the 

 lake water in any part of the area except at one place where a small 

 quantity of dust had fallen and where a few of the very smallest larvae 

 had escaped. The number found remaining was less than 1 per cent 

 of the total counted in the examinations made previous to dusting. 



SUMMARY 



Dusting Paris green from airplanes to control the breeding of 

 Anopheles mosquitoes was tried in 1923 and 1924 on the extensive 

 swamp and marsh areas in the vicinity of Mound, La. Army model 

 DeHaviland planes were employed and were operated by United 



