Sooner or later every flock that goes outside and is exposed to wild birds, will get mites or lice. Just be ready to find the problem, and treat appropriately, so you don't have nice hens die, like I did one winter. I still feel guilty; didn't see the problem until the third bird died! Permethrin spray concentrate is available at my local TSC, and it's by far the easiest treatment method! I check many of my birds at least every couple of weeks, and this fall after having mites in the flock, I'm checking every few days. Mary