Ivermectin does have an egg withdrawal period, but I forget how long. I eat them anyway, as do some others here. That's up to you, at your own risk, but if you're selling eggs, don't, to be safe. For feather (depluming mites) you need to work from the inside as they live in the feather shaft and sprays won't work. I've dealt with them a few times, and in addition to treating now, I will also recommend doseing right as they start their molt. It's good to have the Elector on hand, for red or fowl mites anyway. You can check for red mites at night, run a white paper towel underneath the roost. If it comes out smeared with red, you've got those too.