MITES 227 



suckers on their feet, or the long tactile hairs which are characteristic of 

 most ectoparasitic mites, and these structures are missing in Cnemi- 

 docoptes. In addition their legs are very reduced and the mouth- 

 parts greatly modified. 



An interesting family of mites is the Gheletidae, members of which 

 are predacious and hunt the true feather mites in the bird's plumage. 

 Some have abandoned this symbiotic way of life and have turned para- 

 site. The species of the genus Syringophylus live inside the quills of pigeons 

 and poultry and their bodies have become greatly elongated and pro- 

 foundly modified in shape to suit their long narrow habitat. In this 

 way they resemble the quill mites of the Analgesidae, which are also 

 slim and elongated. The quite unrelated and abundant hair-follicle 

 mites (Demodicidae), which are parasites of mammals, show a similar 

 type of adaptation; they have long cylindrical bodies and their legs are 

 reduced to mere stumps. 



The genus Harpyrynchus is also truly parasitic. They live in the 

 feather follicles of passerine birds which they enlarge to form tumours 

 about the size of peas. These are located chiefly on the flanks and 

 wings of the host. The females never emerge from these tumours and 

 only the immature stages are "free". In shape they form a great con- 

 trast to Syringophylus. Far from being long and narrow they are almost 

 circular with stumpy legs reminiscent of the itch mites. Sometimes 

 colonies of Harpyrynchus destroy the follicular bulbs over large areas of 

 the birds' bodies, thus causing a sort of feather mange. 



The Laelaptidae are essentially parasites of mammals, especially the 

 small rodents, but a few species are found upon birds. Eulaelaps novus 

 appears to be confined to the sand-martin, and Ptilonyssus nudus is 

 recorded from the song thrush and various small passerines in Britain. 



The brilliantly coloured harvest mites (Trombidiidae) are parasitic 

 in the larval stages although free-living and predacious as adults and 

 nymphs. They are often found in great numbers on game-birds, 

 thrushes and other ground-loving species. They attach themselves to 

 the skin, which they pierce, and feed on lymph. 



Mites of the family Tyroglyphidae, known as cheese mites owing to 

 their predilection for that particular delicacy, are often found in birds' 

 nests. They feed chiefly on decaying organic matter, but some are 

 predatory or parasitic. During development many species pass through 

 a dispersal stage known as a "hypopus nymph". The tgg hatches as 

 usual into a six-legged larva, which in turn sheds its skin and becomes 



FFC— Q 



