Airplane Dusting in Control of Malaria Mosquitoes 5 



In the second patch of woods the conditions for dusting were ex- 

 tremely difficult, as the timber was very tall and the growth was so 

 dense that the ground was almost completely shaded. Two lines of 

 glass plates were placed on the ground as before, except that they 

 were spaced at 100-foot instead of 75-foot intervals. Three tests 

 were made with the dusting plane, in none of which was there fail- 

 ure to find Paris green on some of the plates. In one case 8 of the 

 glass plates in one line and 7 in the other -were dusted. For the 

 three flights, the average width of the strip which received 5 or 

 more granules per square inch was about 300 feet, and the average 

 width of that receiving 10 or more grains per square inch was about 

 200 feet. It was thus shown that, even in dense woods, it is possible 

 to reach the ground through the cover of vegetation, although much 

 of the material is lost because it adheres to the leaves or drifts away 

 with the wind. 



In Table 1 is given a summary of the dusting operations over the 

 wooded areas. 



Table 



1. — Airplane dusting over dry woods to determine distribution of the 

 poison on the ground underneath, Mound, La., 1923 



BUNKUM WOODS 



Date 



Mixture 



Number 

 of trips 

 across 



Number 



of glass 



plates 



dusted (2 



lines of 10 



each) 



Width 

 of strip 



Number 



of glass 



plates with 



10 or more 



grains of 



Paris green 



per square 



inch 



Width 

 of strip 



1923 

 July 12 



15-100 

 10-100 

 10-100 

 10-100 



2 

 2 

 3 

 3 



6 



6 

 6 

 7 

 9 

 10 

 10 



Feet 

 450 

 525 

 450 

 450 

 525 

 675 

 750 

 750 





 

 2 

 

 4 

 6 

 10 

 8 



Feet 

 



13 



17 



is :.... 





 150 





 300 

 450 

 750 

 600 



ASHLEY WOODS 



July 13 



17 

 18 









Feet 





13-130 



3 



3 



300 



2 







3 



300 



2 



10-100 



2 



8 



800 



2 







7 



700 







10-100 



3 



4 



400 



2 







5 



500 



3 



Feet 



200 

 200 

 200 

 

 200 

 300 



Five pounds of Paris green in 100 pounds of dust. 



DUSTING MOSQUITO-BREEDING LAKES 



Following these trials the dusting of mosquito-breeding lakes was 

 undertaken, and three locations were selected as offering suitable 

 conditions for the tests. These conditions were an abundance of 

 larvae in the water and proximity of the areas to open fields. The 

 latter was of importance as a possible measure of safety in the event 

 of a forced landing. It was desirable, moreover, that the lakes 

 should be as accessible as possible from solid ground, because much 



