I haven't run into waterfowl lice, and I'm sorry that you have -- pretty much everything I could suggest from reading you've already done. This might be a bit of a stretch, but depending on how much the mystery duck is letting you touch him/her, is there any chance of giving a mild apple cider vinegar and water bath? I think just letting the duck splash around in it wouldn't help much, since it wouldn't get down to the skin, but I work as a dog groomer and we treat a lot of skin issues with ACV/water mixes. When my turkey had scaly leg mites one of the treatments I found involved scrubbing his legs with a toothbrush in an ACV mix. (Yeah, right! You try giving a 40#+ turkey a bath he doesn't want...) It helps with a lot of different skin issues and as long as you use a mild mix it doesn't hurt. Plus if they accidentally drink some it doesn't matterm unlike with, say, Dawn dish soap, which is good for a lot of skin issues but shouldn't go in mouths, eyes, or noses if it can be avoided. Then again, Dawn will stun mites and can sometimes smother them, again without harming your critters.
Sorry if that was a kind of a run-on train of thought. Since I don't have experience with this exact issue it seemed worthwhile to include my thought process in case there are any glaring issues with my logic! If I think of it I will ask my friend who works at the local wildlife rescue. I've 'inherited' several abandoned domestics from her, and she's always confirmed a lack of parasites before sending them my way.
The DE seems to be taking care of it for now, but if the duck still has problems in a couple weeks I'll do the ACV or the dawn.
, including the only Bielefelder pullet. I hope the one set to hatch this weekend do better. I'm going to reduce the humidity in the hatcher and see if that helps.
