196 THE GROUSE IN HEALTH AND IN DISEASE 



whose larvae live in curious, white, papery cases inserted into 

 each twig of this rush-head which they eat. When the rush 

 is in its turn eaten by the Grouse, the larvae of the moth pass 

 into the alimentary canal of the bird and are there digested. 1 

 The case is whitish, semi-transparent, and with brown specks : 

 it is formed when the larva is no longer young, but not at any 

 very fixed time. At first its outer end is closed. The larva 

 often leaves the case, burrowing into the rush-head for food, and 

 at times fails to find its way back. Before pupating, the outer 

 or anal end of the case is opened, and the case strengthened 

 by a glandular excretion. In the Interim Report of the Com- 

 mittee it was recommended that these larvae should be searched 

 for cysts; but it has been pointed out that there would be 

 little chance of the larvae coming across the eggs of the tape- 

 worm as they feed in and on the interior of the rush-head, and 

 the search has yielded no results. 



In following up this second line of research the insects 

 which occurred most commonly in the crop of the Grouse 

 were examined first. These were examined microscopically, 

 both after teasing the body up in glycerine and by grinding it 

 up but not too finely in a pestle ; in some cases also sections 

 were made and examined, but always without result. 



In hunting for the cysts the observer meets with two great 

 difficulties : firstly, it is not exactly known what the cysts of 

 either of the tapeworms are like ; and, secondly, the tissues of 

 the insects and spiders which were examined are little, if at all, 

 known, and more than once some organ proper to the insect has 

 been taken at first sight for a tapeworm cyst, only to result in 

 the disappointment of finding later that it was an egg or other 

 structure belonging to the putative host. 



A considerable number of the commoner insects found on 



1 It has not yet been possible to determine finally the species of the moth, but it 

 is probably Coleophora ccespititiella, for this species frequents many kinds of rush ; 

 whereas the C. glaucicolella, the other inland species, is most partial to Juncus glaucus. 

 The former is usually fully out by the middle of June and lingers on till the middle 

 of July ; the last-named moth issues about the middle of July, and flies for four weeks. 

 J. H. Wood, Ent. Mag., 2nd Ser., iii. (xxviii.), 1892. 



