THE ECTOPAEASITES OF THE RED GROUSE 359 



four hairs, of which one is far longer than the others ; other symmetrically 

 arranged hairs also occur. In the middle line is the proboscis ; this consists 

 of two lateral, moveable, palp-like structures, each bearing hairs and terminating 

 in a stout bristle. These structures are presumably the maxillary palps. Then 

 there is a median very mobile structure, which is the sucking tube ; this moves 

 in all planes, and may be protruded or withdrawn. Its mouth shows a somewhat 

 plicated orifice, and behind it undoubtedly ends in a sucking pharynx. This 

 median structure is probably homologous with the second maxillae or the labium. 



The feet of the Grouse-fly are large but very beautiful. In PL LV., Fig. c., will 

 be found a coloured sketch of a foot seen obliquely. From this drawing it will 

 be seen that the large paired claws are double, and that whereas the distal limb of 

 each claw is slender, and very sharply pointed, the proximal limb is much stouter and 

 ends bluntly. Between the claws is a median, feathered process with hairs or bristles, 

 and at the base of each double claw is a pulvillus covered with minute hairs. 



We do not know the exact relations of the Grouse-fly to the Grouse. It is 

 believed to suck its blood, and it will certainly bite human beings. For a time it 

 seems to burrow amongst the feathers of the bird, and any one handling Grouse 

 during the summer is likely to disturb a fly or two. They come buzzing out, and 

 are apt to crawl up one's sleeve by aid of the pair of great hooked claws on their 

 feet. Altogether they have a sinister aspect, and to people who do not like flies 

 they are very repellent. They occur freely in larders where freshly-killed Grouse 

 have been placed, and after a short time they leave their dead host and accumulate 

 upon the windows. 



The earliest month in which we have found the Grouse-fly is June. The latest 

 we have found it up till the present time is September. In Caithness they have 

 been taken as late as October. Perhaps they are most plentiful in August. 



The females seem to be commoner than the males, or, it may be in August they 

 are more readily taken. Like other members of the Hippoboscidse, which includes 

 the horse-fly, forest-fly, and sheep-tick, the Grouse-fly does not lay eggs, but the 

 ovaries produce one large ovum at a time, and this passes into a dilated oviduct 

 which acts as a uterus, and here the egg develops. After attaining a certain stage 

 of development, the larva surrounds itself with a pupa-skin, and is extruded. The 

 chitin covering the larva hardens and blackens with exposure to the air, and forms 

 the so-called pupa-case ; in fact, one may almost say the young are hatched as 

 pupse. At no time is the larva exposed, though there is a larval stage free in 

 the uterus wrapped first in the egg-shell and then in the pupa-case. 



