Smithsonian Report, 1948.—Knipling PLATE 4 
One type of cage employed in conducting DDT laboratory tests. Various 
concentrations of DDT employing different kinds of formulations were tested 
as a residual treatment to determine the duration of effectiveness against 
mosquitoes and flies. 
Ree 
2. A. W. Lindquist and H. G. Wilson applying a residual or surface spray in an 
army installation. The development of the residual treatment principal of 
mosquito and fly control probably represents the greatest single advancement 
jn our war on insect vectors of diseases. 
