The mites we are seeing mostly here in Utah are the orange/brown color. Yes, check the vent first. Just separate her feathers between the tail and fluff part of her bum. If she has a lot, you will see them squirming around. All in a bunch if she has a lot. Not so much under the wings, in fact, I never have seen any under the wings when mine have been covered around the vent. Chest yes. Sides of tail yes. You have fun tomorrow checking that poor girl out, then let us know how it went. Let's hope it's an easy fix. You don't have to get the bacon grease out. Just the wesson oil or whatever you have.