226 FLEAS, FLUKES AND CUCKOOS 



magnificent clasping legs — symbol of masculine virility in the acarine 

 world. Another group of genera is found on the feathers of the wings, 

 flanks and back of passerine birds. Some are confined to a single host 

 and others occur on a wide variety, but the majority favour certain 

 definite families and groups of birds such as finches, tits, crows or 

 thrushes. Typical British species are Trouessartia minutipes which is 

 peculiar to the house-martin, Joubertia microphyllus (Plate XXXIa) 

 which is found on the chaffinch and tits, and Proctophyllodes glandarius 

 which occurs on a wide range of hosts. 



Certain wing mites [Oustaletia pegasus) found in the tropics on the 

 hornbills (Bucerotidae) have the dorsal setae modified to form feather- 

 like expansions. A superficial glance conveys the impression that they 

 are winged, hence their Greek name. 



Members of another group of the feather mites live next to the skin 

 of the bird, at the base of the fine down feathers, and probably feed on 

 scurf and skin debris. Microlichus avus from the jay and sparrow and 

 Epidermoptes bilobatus from the fowl are typical examples. 



Although all true feather mites lay their eggs on the feathers, in 

 some genera and species such as Falculifer rostratus from doves and 

 pigeons and Pterolichus obtusus from the partridge, the second nymphal 

 stage is passed in the fatty tissues beneath the skin of the bird. In the 

 case of Michaelichus bassani from the gannet, the membranes lining the 

 subcutaneous air-cells are selected, where the mite is often present in 

 large numbers. The males of this species are generally asymmetrical; 

 the only "normal" specimens have been found by Turk on gannets 

 from Great Saltee Island. 



Closely related to the itch mites are the lung mites (Cytolichiidae) 

 which are found in the bronchial tubes and lungs of birds. Sometimes 

 they invade the air sacs and even bone cavities in such numbers that the 

 birds die of suffocation. Well known species in Britain are Cytodites nudus 

 from the pheasant and turkey and Laminosioptes cysticola from poultry. 



The true itch mites (Sarcoptidae) are best known as parasites of men 

 and dogs and are the direct cause of scabies and mange, but some 

 species also attack birds. Thomas Mouffet described them vividly, 

 *' always lying under the outward skin and creep under it as Moles do, 

 biting it and causing a fierce itching." Familiar itch mites are the 

 species which cause scaly leg and de-pluming mange in poultry, 

 Cnemidocoptes mutans (see p. 228) and C. gallinae. As they pass their 

 whole life beneath the skin they have no use for the adhesive 



