These photos show state-of-the-art insect control in late 1941. Walter and his USDA colleagues had discovered that the dog flies (Stomoxys calcitrans) infesting the Panama City, FL area bred in decaying organic matter along the area’s beaches. To get rid of the flies, the team loaded barges with oil and creosote, then mixed the two petroleum products and sprayed them on the beaches and marsh grasses all along the shore. This sounds completely horrifying by modern environmental standards – the resulting oil slick must have extended for miles – but these were the tools available at the time.

Late September 1941