360 THE GROUSE IN HEALTH AND IN DISEASE 



When first deposited the pupae are light in colour, and the case has not 

 hardened. Those dissected out from a fly are shorter and more squat than the 

 mature pupae found on the ground, and the symmetrical ridges and elevations are 

 much less well marked. 



The pupae were found during August and September. They appear to be 

 deposited amongst the feathers, and are easily detached from them. The few 

 we have found either dropped on some paper over which we were handling some 

 birds, or lay loose at the bottom of the cardboard boxes in which Grouse travel. 

 Probably they take some eight or nine months before they give rise to the imagos, 

 and the latter very likely disappear altogether from about October till June. 

 Further research is needed to throw light on these questions. 



Three specimens of 0. lagopodis, all of them taken from one Grouse, were 

 themselves markedly infested with an ectoparasite, a species of mite. Here I 

 refrain from quoting Dean Swift. The mite belongs to the genus Canestrinia, 

 as my friend Mr C. Warburton has kindly told me, and is probably a new species. 

 The subfamily Canestrininae are all parasitic upon insects, and are regarded as 

 harmless. Our specimens existed in considerable numbers, clustered round the 

 hinder end of the fly's abdomen on the ventral surface, with their proboscides 

 plunged into its body. Many were laying eggs, and many cast- off cuticles were 

 lying around. Eggs from which the larvae had escaped presented a spindle- 

 shaped outline ; others contained ova in various stages of differentiation ; others 

 fully formed larvae. 



We have in no single case found a Grouse-fly in the crop of a Grouse, nor 

 have we yet found any cestode larvae or cysts in the bodies of the flies which 

 we have cut into sections or dissected. 



(ii.) Fam. Scatophagidae = Scatomyzidae. 



IV. SOATOPHAOA STERCORARIA L. 



This fly cannot be looked upon as an ectoparasite of the Grouse, but it lays its 

 eggs in Grouse-droppings, and its maggots live on and in these dejecta. The 

 maggots must therefore constantly be in close contact with and possibly eating the 

 ova of the tapeworms which exist in such vast numbers in the Grouse-droppings ; 

 and hence we thought it was a profitable object to investigate for the cysticercus or 

 second stage of the cestode. It should be mentioned that the droppings consist of 

 two parts : (1) the dejecta from the intestine strictly speaking, and (2) the more 



