MITES BORNE BY MUSCID FLIES 



157 



the Lesser House-fly, F. canicularis, caught in a romu ; on the 

 underside of thi' fly's abdonu'ii a number of immature Gamasids 

 are attached, apparently by th<'ir stomal regions. Mr Micliafl, to 

 whom I submitted these mites, said that it was extremely difficult 

 to identify immature Gamasids owing to the scarcity of our know- 

 ledge as to their life-histories, but he stated that they were very 

 like Dinychella asperata Berlese. 



These specimens may be truly parasitic, as I am inclined to 

 believe, since many Acari are parasitic in the immature state, 

 although the adults may not be so ; on the other hand this form 

 of attachment may be employed as a means of maintaining a wun-a 

 secure hold of the transporting insect. 



Fig. 71. Thoraco-abdominal region of Fannia caniculnri.t, ? , showing Gamasids 

 attached to the ventral side of the abdomen. 



Ewing (1913) describes a new species of Gamasid mite Macro- 

 cheles muscae which is parasitic on M. domestica, always attaching 

 itself, according to the author, in a deflnite place, namely, at the 

 base of the abdomen on its ventral side, the anterior end of the 

 larva being directed forwards. It feeds on the host. Its colour is 

 dark yellowish brown; length 0'97 mm., width 0"62mm. It has 

 been found in the States of Oregon and New York. 



Hamer (1909) records Gamasid mites as particularly affecting 

 Muscina stabiilans, especially in early June. 



