MOOR MANAGEMENT 325 



are each capable of producing many eggs ; these eggs pass from 

 the body with the caecal deposit, and after three days' incubation 

 on the moor, reach the larval stage. The caecal deposit is well 

 known to all field observers, and is readily distinguished from 

 the hard cartouche-shaped dropping of the main intestines 

 by its light chocolate brown appearance and moist consistency. 



The number of the larvae in a Grouse-dropping varies 

 enormously, and depends directly on the degree of infestment 

 of the bird from which it comes ; in the case of heavily infected 

 birds they may be reckoned in tens of thousands. 



The larvse during the earlier stages of their existence appear 

 to have the power of lying dormant for an indefinite period, 

 they are not affected by the frost ; a rise of temperature will 

 at any period raise them out of their torpid condition ; excessive 

 drought and perhaps the salt spray of the sea are the only 

 conditions known to be injurious to their health. 



After passing through the casting of skins common to most 

 nematode worms, and after a period generally to be reckoned 

 in weeks, but probably never less than ten days, the larvse 

 assume a resistant sheath and become active young nematodes ; 

 they climb the shoots of the damp heather, and, like the East 

 Coast fever-tick on the South African spear-grass, lie in wait for 

 an opportunity to complete their life history by returning to 

 their natural host the Grouse. 



Once the Strongyles have returned to their host the further 

 stages of their life history follow in rapid succession. Absorbed 

 with the heather shoot into the crop, protected in the gizzard 

 by the sheath-like covering from the action of any but the 

 sharpest grits, the encysted Strongyles pass once more into 

 the caecum, and on the third day reach the adult stage ; the 

 females become fertile, and three days later the myriad offspring 

 set forth once more to infect the moor. 



It is only when the adult Strongyle is found in the caecum 

 in large numbers that the health of the Grouse is appreciably 

 affected. If we consider that birds may be packed on one 

 portion of the feeding area, for perhaps weeks at a time, herded 



