I'm concerned my hens may have mites or another parasite but am unsure what to look for. Egg production has been down for about 2 weeks. We just expanded their coop into a new shaded area; and the egg production decrease corresponded with the expansion so I thought it was stress and because they didn't have access to oyster shell for a few days. But I had thought production would be back up by now if that were the cause. Tonight when I went in the hen house to check them on the roost, several were shaking their heads as if annoyed by an insect. So I'm thinking mites or another insect. We've had a lot of biting flies on our farm this spring - I added Rosemary sprigs to the hen house today and that seemed to do the trick, but the head shaking was going on without visible insects. Does anyone have advice for what exactly I should check to confirm mites or lice or other insect? Thanks!