338 Ewing, English Sparrow and Bird Mites. [july 



upon it. The number of feathers thus used in the construction of 

 the nest was at least more than 200. I estimated them at 250. 

 Multiplying this number by the number of individuals found en a 

 single feather would give the total number of 18,000 individuals 

 of the poultry mite found in only a single nest of the sparrow. 



This case, though the worst found, will give some idea as to 

 what are the possibilities of infestation of a chicken house or roost 

 by means of the sparrow; and of the annoyance which these mites 

 may give to other fowls or domestic animals, and, as I have 

 found in one case, to man himself, when the mites are com- 

 pelled to leave an abandoned sparrow nest and begin to wander 

 and seek food elsewhere. 



The Differences between the Chicken Mite and the Bird 



Mite. 



After studying some scores of mounted specimens, and after 

 observing hundreds of live individuals of both of our common 

 species of Dermanyssus, the author submits the following characters 

 which are amply sufficient to separate the two: 



Dermanyssus gallinoe Dermanyssus avium 



1. Mandibles of the female very 1. Mandibles of female very 

 long and needle-like, not chelate slender but not needle-like, and 

 (Fig. 2, a). [By dorso-ventral pres- seen to be distinctly chelate (Fig. 

 sure they may be protruded.] 2, b). 



2. Mandibles of male, seen to 2. Mandibles of the male, nor- 

 be chelate, but one of the arms of mal, and not differing essentially 

 the chela? especially long drawn from those of the female (Fig. 2, d). 

 out and curved (Fig. 2, c). 



3. Females becoming, at times, 3. Females but little larger than 

 much larger than the males, often males. Never over 1.00 mm. long, 

 as much as three times, due to 



engorgement with blood. Length 

 may be over 1.00 mm. 



Inoculation Tests. 



Some time previous to the finding of the badly infested sparrow 

 nest, a healthy young chicken was procured for experimental 

 purposes. This chicken was kept in a large, clean goods box for a 



