Mites Injurious to Domestic Animals. 87 



Genus DermanyssHS, Dugs, 1834. 



This genus is chiefly characterised by the thin stylets (chelicerae) 

 which are of considerable length in the female sex, being well 

 adapted for piercing the skin of the host (fig. 54) . Only five species are 

 known, two of them being found on birds and three on rats. One 

 of the species found on birds {D. gallinae, figs. 55-61) is the common 

 red mite of poultry and cage birds ; the other (D. jyasaerinus) is a 

 parasite of the common sparrow and apparently restricted to that 

 host. 



One of the species of Dermanyssus parasitic on rats {D. muris, 

 Hirst, fig. 62), chiefly found on the black rat, is widely distributed, 

 having been recorded from Egypt, Arabia, India, Ceylon, and 



HrJJeyil. 



Fig. 74. 



Raillietiaauris ip- 91). (a) Second leg of male, (b) Chelicerae 

 of male. (Original.) 



Formosa. The other two (D. sanguineus, Hirst, fig. 63, and D. 

 aegyptius, Hirst, fig. 64) have so far been found only in Egypt. 



Dermanyssus gallinae, Redi, 1674. 

 (Fig. 55-61.) 

 The colour of this well-known pest of poultry varies from whitish 

 to dark red, according to the amount of ingested blood. The 

 larva can transform itself into the next stage (first nymph) without 

 taking any nourishment. The complete life cycle from egg to 

 adult is said to take about seven days. 



Dermanyssus gallinae is of considerable economic importance, 

 being very abundant in many fowl-houses in Europe and North 



