Do the ducks have access to swim water? I would not dust the ducks due to my concern about getting the dust in their lungs, but would get some Flea Busters and put it where the walls meet the floors in the coop - tuck it in really tight (it's pH-adjusted borax, I believe).
Not criticizing anyone who puts DE on the ducks directly, I would just be hesitant. And since ducks swim, the DE would not last long enough to be effective . . . just thinking out loud.
Not criticizing anyone who puts DE on the ducks directly, I would just be hesitant. And since ducks swim, the DE would not last long enough to be effective . . . just thinking out loud.