I have found Northern fowl mites on some of my hens. I will treat my coop and flock soon, but would like to continue to sell eggs. So... Here are my questions: 1.) I understand that permethrin is labelled for use on poultry, but that there are a lot of problems with mites becoming resistant to it. I have also heard that people are using ivermectin pour-ons, but that the use is off-label. What would you feel safe using if you wanted to sell eggs at your farm market later on down the line? 2.) Is a spray more effective that a dust application of permethrin? 3.) Does sulfur dust work? I haven't heard any tales of mites becoming resistant to that. Many thanks in advance.