I just put another of my ex batts out of her misery, 2nd in 10 days - not a sign of mites anywhere but have stripped out and disinfected the shed in case. No real symptoms, just hunched up, drinking and eating occasionally, not moving about much, then just sitting hunched in a corner at the end, but when I did the deed she was skin and bone so must have been going down hill for a while. No mucous, coughs or sneezes. Crop OK, didn't seem to be egg bound either. Just a mystery.