OTHER ITCH-MITES. 



79 



distinct species of mites belonging to three different genera. 

 As but very few of these parasites cause real injury to 

 their hosts excepting if they should become very numerous, 

 it is not necessary to describe them in detail. In extreme 

 cases they disturb, locally, the formation of feathers, and 

 may, by deranging nutrition, cause a fatal consumption. 

 Proper cleanliness in poultrj'-houses and bird-cages will 

 greatlv lessen their numbers. 



Fig. 43. Mite infesting bird, 

 male. Greatly enlarged. Origina 



Fig. 44. Mite infesting bird, 

 female. Greatly enlarged. Origi- 

 nal. 



There are a number of other mites, belonging to different 

 families, which can also, in extreme cases, cause itch-like dis- 

 eases. Such mites are not usually found permanently upon 

 man and domesticated animals, but only occassionally in- 

 vade them. 



But it is not alone the skin of animals that is inhabited 

 by mites; even the air-sacs of chickens are invaded by white 

 mites large enough to be seen with the naked eye. Such para- 

 sites ( Cijtodiiei< nudusN'\z\oX\) enter the bronchi and may even 

 reach the interior of air-canals in the bones. If not numer- 

 ous their presence is not detected, but if favored by suitable 

 conditions they increase rapidly in number and kill their 

 hosts. An autopsy revealed them also in the lungs, liver, 

 and kidney. Another species of mite {Symplectoptes cystlcola 

 Vizioli) causes an irritation in the connective tissues, form- 

 ing tubercles, inside of which they may be found; they also 



