With all the birds I have, so far I don't see any parasites. But, if wild birds feast on your feed, It will expose your flock. I had a cardinal that got caught in the netting, trying to come in to feed. Poor guy was terrified and I had to cut the netting to release him. Wild birds will really cause problems, so I just watch close. I only feed in the coop run, but when they free range who knows? Ivermectin pour on is a really good product, and can be used by drops to remove parasites from your flock. It supposedly does kill mites also. Its labeled for cattle but I use it on my pug, all my birds. will post the dosage as soon as I can find it. I recently ran across a better product Valbazen but have not tried it yet. It does take time to drop the meds on each bird, but better to be safe.