It is not uncommon for broody hen's nests to become overrun with mites when they are brooding. They provide a 24/7 banqueting opportunity for the mites. She has done incredibly well to stick to her eggs until they hatched despite the infestation. I've seen broody hens abandon nests with just a few days to do because they were crawling with mires and being eaten alive. The chances are, the blood spots you saw were where the mites had been sucking the chicks' blood or perhaps been pecked or scratched at due to the irritation. It is possible that the chicks died because they had crush injuries due to the broody being irritated by the mites instead of focussing on her chicks. I now always dust my broody hens' nests with DE prior to setting them and a couple of times during the incubation period to keep mites to a minimum, since I had that incident I mentioned where my broody abandoned her nest and I was horrified to see the eggs in it crawling with mites.
The gaping you describe the chicks doing is most likely due to respiratory system injury
I think it is unlikely to be coccidiosis because broody reared chicks are much more resistant to it and also some of them died before they had even eaten anything. I think the mites are the cause of your problems and have possibly resulted in accidental crushing of the chicks by the broody.
To treat the coop, you can try using the DE until you get something stronger. Get a crate or large cardboard box and reunite the broody and chick asap. If the broody has had a chance to dust bath and rid herself of most of them, she should be better able to care for the chick. As regards treating the coop, I use a soft dustpan brush to dip into the DE and then dust it into all the nooks and crannies of the coop but particularly around the roost and nest box areas. Obviously wear a mask and remove all bedding material and sweep it out thoroughly before you start. I would keep the broody and chick in the cardboard box in a garage or shed or even spare room overnight to let things settle. It takes a few days to take effect because it kills by dehydrating the mites. I would definitely invest in some permethrin spray for the future though as this will almost certainly be a recurring problem in the coop. You will probably need to retreat the coop at weekly intervals for a few weeks before you bottom the problem. Anywhere that there is a gap in the coop is where the mites will live and breed and then they crawl out to feed on the chickens by sucking their blood whilst they are roosting at night, or in the case of a broody, the whole time she is on the nest.
The gaping you describe the chicks doing is most likely due to respiratory system injury
I think it is unlikely to be coccidiosis because broody reared chicks are much more resistant to it and also some of them died before they had even eaten anything. I think the mites are the cause of your problems and have possibly resulted in accidental crushing of the chicks by the broody.
To treat the coop, you can try using the DE until you get something stronger. Get a crate or large cardboard box and reunite the broody and chick asap. If the broody has had a chance to dust bath and rid herself of most of them, she should be better able to care for the chick. As regards treating the coop, I use a soft dustpan brush to dip into the DE and then dust it into all the nooks and crannies of the coop but particularly around the roost and nest box areas. Obviously wear a mask and remove all bedding material and sweep it out thoroughly before you start. I would keep the broody and chick in the cardboard box in a garage or shed or even spare room overnight to let things settle. It takes a few days to take effect because it kills by dehydrating the mites. I would definitely invest in some permethrin spray for the future though as this will almost certainly be a recurring problem in the coop. You will probably need to retreat the coop at weekly intervals for a few weeks before you bottom the problem. Anywhere that there is a gap in the coop is where the mites will live and breed and then they crawl out to feed on the chickens by sucking their blood whilst they are roosting at night, or in the case of a broody, the whole time she is on the nest.
