LOUSE-FLIES. 



139 



I. LOUSE-FLIES. 



{lUppoljoscido'^ Puplparci) . 

 Louse-flies are very peculiar insects, belonging to the 

 order of flies (Dijjfera); both their form and mode of repro- 

 duction are very abnormal. They are parasitic, living upon 

 the bodies of mammals and birds. Closely allied insects, 

 with similar life-histories, are found upon bats and the honej'- 

 bee. Some louse-flies are winged, others are not, bitt in the 

 latter case we find on each side of the thorax, near the an- 



Fig. 120.— Sheep-tick and enlarged foot. Greatly enlarged. Original. 



terior angle, a small round spot, indicating where the upper- 

 wing should be, and near the posterior angle a small pro- 

 jection which seems to represent the balancers, or remnants 

 of hind wings. All louse-flies possess a depressed body and 

 widely separated, short, and stout legs, furnished with 

 strong claws, which in some cases have teeth. The last joint 

 of each foot bears a feather- like organ, probably used to coil 

 around the hair for a stronger foothold, (see enlarged foot 

 in fig. 120). The head, nearly as wide or wider than the 

 thorax, is sunk in the same without a distinct neck; the 

 feelers are very short, apparently one-jointed, with a termi- 



