MITES 225 



Irish record. All the red mites are true blood-suckers and when present 

 in large numbers they may bleed the host to death. They are also 

 carriers of relapsing fever of birds. Fonsecaonyssus sylvarum, also a type of 

 red mite (Macronyssidae) which attacks poultry, pigeons and wild 

 birds, has been found to be naturally infected with the virus of western 

 equine encephalitis. Another related group sucks the blood in the nasal 

 cavities of birds, such as sparrows, bullfinches, swallows, dippers, eider 

 ducks and so forth. There are records from the Shetland Isles of 

 Rhinonyssus neglectus from the purple sandpiper, S terms tomum cale- 

 donicum from the guillemot and S. waterstoni from the little auk, and 

 several related species from various hosts. 



Among the true feather mites the Analgesidae are the most familiar 

 on birds, and over 150 species are known from Britain alone. These 

 mites are not blood-suckers but feed upon the horny layers of the skin 

 and the feathers. Some genera are found exclusively on the pinions 

 (rectrices) of relatively large birds. Two well known examples are 

 Pterolichus ardeae on the heron and P. cuculi from the cuckoo. Occasion- 

 ally a species favours a circumscribed area of the pinions, such as the 

 white portions of the wings of the nightjar, and is not to be found any- 

 where else. Certain other genera, notably Syringobia from various 

 waders, including the sanderling and green sandpiper, and Thecarthra 

 also, from plovers and gulls, inhabit the quills of some of the larger 

 feathers and feed upon the pith. They seem to know when the moult is 

 due, for they are never found in cast feathers. They lay their eggs in 

 neat spirals inside the quill and if no male happens to be in the same 

 feather with the females, they resort to virgin birth. The genus Analges 

 and its allies contain mites which are found on all parts of the bird's 

 plumage except the pinions. The specimen of ^. chelopus illustrated on 

 Plate XXXIb, was taken from the hedge-sparrow. The enormously 

 enlarged third pair of legs of the male is a characteristic feature of these 

 mites. They are not used for fighting but serve to lock the female in a 

 firm embrace during copulation. In some species such as Megninia 

 strigis-otis from the short-eared owl the male seems to stimulate the 

 female by making passes over her with his huge legs and does not resort 

 to force. In other cases (such as Protalges attenuatus from the barn-owl) 

 his fierce love-making permanently dents her cuticle. These mites 

 normally copulate precociously, before they are mature. If no female 

 is available they pay a high price for their enforced virginity, for 

 development is retarded or even arrested, and they fail to grow their 



