PLATE 6 
Smithsonian Report, 1948.—Knipling 
1. B. V. Travis, A. W. Lindquist, A. H. Madden, and A. L. Smith with research 
subjects testing mosquito repellents in the field. 
(U. 8. D. A. photograph by Knell.) 
2. Testing miticides. Several thousand candidate materials were tested. The 
initial test procedures consisted of “stopping time’’ tests. Here F. M. Snyder 
(center) and assistants are placing chiggers collected in infested areas on cloth 
patches treated with miticides to determine if they are effective miticides. 
