Bluebird Ectoparasites

After my post about avian pox, another annoyance for birds: ectoparasites. Nest mites are common on bluebird chicks (picture below with blood-filled dots). Crossing my fingers, I have never had blowfly larvae on my trail. But, the one ectoparasite that is new to me and apparently uncommon for the South is the Black Fly (picture below) which also sucks blood. Interestingly, chicks can have a heavy load of mites and still develop well, but a few black flies can kill them and the nestlings presented here with black flies did die...