1911] oil Grouse Disease. 15 



which is apt to crawl up the sleeves of those who handle grouse in 

 the early autumn. The grouse-fly Ijelongs to the same group as the 

 horse-fly and the sheep-tick. The latter, however, has lost its wings 

 and burrows in the wool of the fleece. Most members of the family 

 to which this grouse-fly l)elongs Hve upon birds ; it particularly 

 frequents swallows and other alhed species. Recently Dr. Sharp has 

 pointed out that the grouse-fly {Onithomyia lat/opodis) is distinct 

 from the ordinary bird-fly (0. avicularia). The habits of the grouse- 

 fly are diflicult to investigate. It is beheved to suck the blood of 

 the grouse, and very probably inoculates the bird with some of the 

 protozoa which infests its blood. The adult or imago burrows 

 amongst the feathers of the bird, and any one handling grouse 

 during the late summer is apt to disturl) a fly or two. Their feet, 

 although large, are very beautiful. Each is provided with a pair of 

 most powerful hooks. Altogether, these insects have a sinister aspect 

 and they are very repellent to people who do not like flies. The 

 grouse-fly occurs very frequently in larders where freshly killed 

 grouse have been placed, and after a short time they readily leave 

 their dead hosts and accumulate on the windows. Like the fatal 

 tseste-fly of Africa, which conveys sleeping sickness, they lay no eggs, 

 but produce one larva or maggot at a time, and this immediately turns 

 into a pupa. The pupge of the grouse-fly, usually found in the nest 

 of the grouse during August and September, are black, shiny, seed- 

 like-looking olijects. Probably each pupa takes some three-quarters 

 of a year to develop into the adult fly, and the latter disappears from 

 October until June. There is thus a certain tragedy in the life of 

 these insects. No parent ever sees its offspring, no offspring has ever 

 known parental care. We have never found one of these flies in the 

 crop of the grouse, nor have we succeeded in finding cysts in the 

 bodies of flies which were broken up, or teased up, or cut into sections. 



Finally there is another fly whose larva lives in grouse droppings. 

 All these creatures have been carefully searched for the larva of r,he 

 grouse tape-worms, Init so far with no definite success. 



Of the fifteen endoparasites but two or three demand attention ; 

 the others are comparatively rare or innocuous, and some, such as 

 the gape— or forked— worm so fatal to pheasants, are not normally 

 parasites of the grouse. Occasionally by some accident they get into 

 the wrong Paradise. 



Some of these endoparasites, which live inside the body of the 

 grouse, are responsil)le for the illnesses from which grouse suffer. 

 Any attempt to control their number and their activity must depend 

 on our knowledge of their life-history, hence the stress which has 

 been laid on the external parasites which may function as the second 

 or larval host of some of them. 



At the time the present Inquiry commenced to inquire there were 

 Ijut two worms described as being in the alimentary canal of the 

 grouse — the large tape-worm which lives in the small intestine all the 



