Scaly leg and face mites
Three species are known to infect both the legs and faces in birds: K. pilae, K. mutans, and Procnemidocoptes janssensi.
Knemidocoptes pilae predominantly parasitizes psittacine birds, and many of these birds are Pacific distribution species. Most reports involve
budgerigars (Melopsittacus undulatus), but K. pilae has also been found in Alexandrine parakeets, ring-necked parakeets (Psittacula species), scarlet-chested parrots (Neophema splendida), Princess parrots (Polytelis alexandrae), yellow-fronted Kakariki (Cyanoramphus auriceps), cockatiels (Nymphicus hollandicus), and cockatoos, especially palm (Probosciger species) and sulphur-crested (Cacatua species).4,7
Knemidocoptes pilae has also been seen in several South American birds, such as green-winged macaws (Ara chloroptera) and Amazon parrots (Amazona species).8
Knemidocoptes pilae is smaller than K. mutans, has a heavier chitinous dorsal shield with distinct edges, and is covered by minute punctiform dots.
Knemidocoptes mutans is common in domestic fowl and has been confused with K. pilae.9 Chickens, turkeys, pheasants, and other gallinaceous birds are commonly affected, as are several raptor species. Knemidocoptes mutans can range in size from 350 to 450 μm x 280 to 380 μm in females and 200 to 240 μm x 145 to 160 μm in males. Typically, adult
females are 0.5 mm in diameter.9,10
Knemidocoptes mutans has a strongly striated epidermis; dorsal striations are not interrupted. The shield edges are indistinct, and the anterior
shield is devoid of the minute punctiform dots seen in K. pilae.
Procnemidocoptes janssensi has been found in lovebirds (Agapornis species).11
Scaly leg mites
Two species most commonly infect the legs in birds: K. jamaicensis and K. intermedius.
Knemidocoptes jamaicensis is the scaly leg mite in passerines, primarily in canaries (Serinus canaria), Gouldian finches (Chloebia gouldiae), and mynahs. Knemidocoptes jamaicensis has also been reported in blackbirds, grackles, crows, catbirds, woodpeckers, towhees, and several other species in the United
States and Canada.4 In the 1990s, several episodes of unusual morbidity with mortality were discovered in migratory American robins (Turdus migratorius) from Oklahoma, Florida, and Georgia. As much as 60% to 80% of the population was affected.12 Similar epizootics have occurred in the United States in evening grosbeaks (Coccothraustes vespertinus) and in Europe in migrating chaffinches (Fringilla coelebs).12
Knemidocoptes intermedius has been identified as the cause of skin lesions around tibiotarsal joints in several wild passerine species from Australia
and the United Kingdom.13-15
Three mite species are known to infect primarily the feathers in birds: Knemidocoptes gallinae, Knemidocoptes laevis, and Neocnemidocoptes gallinae.
Knemidocoptes gallinae is smaller than K. mutans (the adult female averages 0.3 mm in diameter) and burrows into the basal shafts and feathers on the epidermis of chickens,
pigeons, and pheasants. It appears to be more prevalent in the spring and summer. Knemidocoptes gallinae has interrupted dorsal striations, forming raised sculpturing.9
Knemidocoptes laevis is a depluming mite in pigeons, and N. gallinae affects pheasants, chickens, pigeons, and geese.9