Old biddy, sorry to hear about losing your peahen. If you do not raise bees, you might want to pick up some Permethrin 10 at TSC or other feed store. It can be mixed with water and used to spray the whole coop every 30 days to get rid of any infestation. Elector PSP is quite pricey, but it is supposed to be very good as well.
Thank you Eggcessive. I still have 5 adult peafowl in the pen and so I am worried about them as well. Yes, I have sprayed the coop with Permethrin 10 and will continue to do so. I have read that Elector PSP is even better to use and am checking that out as well. I am also treating the peafowl drinking water with Corid since I do have chickens in the area - though not inside the peafowl yard - and am worried about coccidiosis as well as the fleas. I wish I were a bird vet and knew better how to take care of my birds. This learning as I go is heartbreaking.