In the book of geese by Dave Holderread he says that if geese a kept in clean surroundings very seldom get lice or mites, but if you raise chickens or turkeys then they are more suseptiable to getting them, you can use Sevin or Mange and Lice control, Malathian, it says be very careful not to get it into feed or water when using. I use Epernix Pour-on because it is easier to use and it's almost impossible to get down to the skin on water fowl with powder. . With the Epernix all you do is part the feathers at the base of the neck where the wings start on the back and put drops on the skin { like you would Frontline for dogs} If you do have an infestation you also need to clean out their sleeping quaters and treat it from top to bottom, and then treat birds and house again in 10 days to kill the eggs that hatch out. If they have bathing water that will also help.