Ornithonyssus bursa (also known as the tropical fowl mite) is a species of mite. It is most often a parasite of birds, but also has been found to bite humans and two species of mammals. It usually lives in birds' feathers, but for laying its eggs, it more often uses their nests rather than their feathers. Tropical fowl mites undergo five stages during their development: egg, larva, protonymph, deutonymph, and adult. During the last two stages, they suck blood from their host for food. They are often diurnal, whereas northern fowl mites are nocturnal in nature.