Abstract
After larval control of blackfly, Simulium aokii, in a stream in Tokyo for 8 years by the application of mixed pastes of DDT 40% and lindane 1.6%, the resistance of larvae has developed highly to DDT and fairly to lindane. The LC-50's given by immersion test for 10 minutes were 7, 300ppm in DDT and 91ppm in lindane. These were far higher than those of blackfly larvae collected from a stream not applied with any chemical, which showed 570ppm and 35ppm of LC-50's in DDT and in lindane, respectively.
