HELP!! red mites on my broody hen!!!!

[collsyl]

I just discovered this morning that my broody hen has red mites.

She is one week away from hatch day.I went to the farm supply and got some insecticide dust to treat all the birds with.They suggested I wait until the chicks hatch to treat as trying to dust her and clean the nest may make her decide not to get back on the eggs. But, I am worried that the chicks will get infected as soon as they hatch.Don't know if I want to be dusting new chicks with insecticide. Does anyone have any experience with this or suggestions Thanks