National Geographic : 1953 Aug
0 National Geographic Society 208 Science vs. Insects: Researchers Test Airborne Spraying Equipment for Fighting Forest Pests Stakes support small aluminum plates. Dye-colored insecticides, loosed from the Department of Agriculture plane, settle on the plates and indicate coverage and concentration. A man (center) contacts the pilot by radio; colored smoke shows wind direction. Insects destroy as much timber annually asforest fires.