Because of the way in which Duet is applied and the time of day it is applied, it should not impact beneficial insects, like bees and butterflies. Duet is applied in small droplets, which break down quickly in the environment. Since the product must hit a mosquito while it is in flight to have an effect, it is sprayed at night when mosquitoes are actively flying and when other insects, such as bees and butterflies, are not active.
However, Duet is an insecticide and may be toxic upon direct exposure to bees active outside the hive. Beekeepers can protect their bees by sheltering the hives during the spraying operations.