The insecticide diflubenzuron, Dimilin, was applied topically to the eggs of Tabanus triceps and Chrysops dispar. Mean per cent hatchability of these eggs at various concentrations ranging from 1 to 150 ppm were observed. The hatchability depended upon the age of the egg and increased with age. A minimal dose of 10 ppm of diflubenzuron caused 100% mortality (no hatchability) at the age of 48 hr in both species. The per cent hatchability was inversely proportional to the concentration of Dimilin. The larvicidal effect of Dimilin was also noted. Larval mortality (100%) was observed after 60 hr treatment. The larval mortality was directly proportional to the concentration of Dimilin. The results show that Dimilin has potential for controlling Tabanid vectors.
