238 THE GROUSE IN HEALTH AND IN DISEASE 



faecal contamination during the winter months presumably 

 ascends the heather. The frequent rains and mists at this time 

 give the larvae ample opportunity to reach the topmost tips of 

 the plant. 



The rapid death of the eggs of Trichostrongylus pergracilis 

 in faeces that have undergone temporary drying indicates that 

 the drier the moor, the more efficacious will wind and sun prove 

 as natural antagonists to " Grouse Disease." Again, as the 

 infective forms of the parasite occur on the " food " heather, 

 it is evident that the greater the amount of " food " heather 

 in proportion to each bird, the less likely it is to become 

 infected. As the periodical burning of heather not only 

 increases eventually the area of food heather, but at the same 

 time destroys in the only effective way known the living 

 parasites upon the area of heather burned, the policy of heather 

 burning, advocated by the Committee upon other grounds, 

 receives additional support. 



The practicability and value of a periodical cutting of the 

 heather requires further consideration by those acquainted 

 with local conditions ; but, if practicable, such a measure should 

 not only be a means of ridding large areas of the moor of infective 

 material, and of bringing about a rapid increase in the " food " 

 heather area, but might also be applicable to those parts of a 

 moor and in those seasons of the year when burning is impossible. 



PART III. INCIDENCE OF INFECTION. 



It is necessary to emphasise the fact that Strongylosis is 

 essentially a spring disease, for hitherto the view has been held 

 that this form of Grouse Disease mortality occurs both in the 

 spring and in the autumn with a break between. The mistake 

 arises from incomplete observation of the facts. 



Owing to the natural objection to the disturbance of the 

 moor in the breeding season the majority of gamekeepers make 

 a point of never searching the ground for dead or sickly birds 



