Diseases of poultry; their etiology, Diseases of poultry; their etiology, diagnosis, treatment, and prevention diseasesofpoultr00pea Year: 1915 External Parasites 227 The mites live on the skin at the base of the feathers. Since the mites are sometimes found on birds which show no signs of scabies and since the disease so closely resembles favus, which is known to be caused by a fungus, it is sometimes supposed that this mange is also due to a fungus and that the mites are inoffensive. Five species of mites have been recorded which live upon the feathers of fowls. These are fairly abundan
Diseases of poultry; their etiology, Diseases of poultry; their etiology, diagnosis, treatment, and prevention diseasesofpoultr00pea Year: 1915 External Parasites 227 The mites live on the skin at the base of the feathers. Since the mites are sometimes found on birds which show no signs of scabies and since the disease so closely resembles favus, which is known to be caused by a fungus, it is sometimes supposed that this mange is also due to a fungus and that the mites are inoffensive. Five species of mites have been recorded which live upon the feathers of fowls. These are fairly abundant but do no harm. Two mites live within the body of fowls. One of these, the air-sac mite, is described elsewhere (p. 180). The other, the connec- tive tissue mite, Sympledoptes cysticola, is found in the connective tissue of the fowls. They produce local irritations giving rise to tubercles, but apparently do not affect the health of the bird. The larvse of the so-called 'harvest-bug' (which isnot a bugat all), T etranychus {T hroiiv- hidium) {Leptus) autumnalis, sometimes attacks poultry. The appearance of this mite is shown in Fig. 48. This small brick red mite, barely visi- ble to the naked eye, is bred upon berry and currant bushes, vegetables and grain, but when opportunity offers it bites al- most any animal, often attacking man. It sometimes causes considerable mor- tality among late hatched chickens which frequent its breeding places. The parasites fasten themselves so firmly by their claws and palpi that they can only be detached by force. They produce intense irritation, which Fig. 47. — Symplec- toptes cysticola. Connective tissue mite. (After Theobald.)
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