63 



British Islands includes two other species of Hippoboscida;, 

 Stenopteryx hiriindhiis, Linn., and Oxypteriim pallidum, Leach, found 

 respectively on and in the nests of the house martin {Cluiidon urbica, 

 Linn.), and the swift {Cypselus apus, Linn.). 



It is doubtful whether an authentic instance exists in which any 

 species of Hippoboscidje has sucked human blood under natural 

 conditions, though the flies sometimes stray on to human beings 

 when their hosts are interfered with. 



Genus 

 HIPPOBOSCA, Linn-xu.s. 



Hippobosca equina, Linn.— The Forest Fly. 

 Plate 31. 



The upper figure shows the resting position. 



As indicated b)' the English name, the . principal home of this 

 species in the British Islands is the New Forest, in Hampshire, where 

 it may often be seen in clusters like bees, sometimes numbering many 

 hundreds, on the ponies and cattle which run wild there. The flies 

 chiefly congregate on parts where the skin is thinnest, beneath the 

 tail, on the perinneum, and on the inner surface of the thighs. The 

 bite does not seem to cause pain, and animals bred in the Forest take 

 no notice of the fly, but strange horses and especially donkeys are 

 sometimes driven almost frantic by the irritation caused by a single 

 Forest Fly crawling over them. The toothed claws enable the fly to 

 cling so tightly to the hair that it is impossible for an animal to 

 dislodge it by a brush from its tail, and the quick and somewhat 

 crab-like movements of the insect, which when disturbi.d usually 

 moves sideways, tickle the host and are exceedingly irritating to 

 sensitive animals. 



Forest flies are to be found from the beginning of May until at least 

 the second week in October. In addition to the New Forest the species 



