50 Journal of the Department of Agriculture. 



and particularly on places where moisture is more or less permanent, 

 viz., vleis, along springs, rivers, etc. In the winter, however, the 

 surface moisture disappears and the larvae crawl into the ground. 

 They have been found as deep as one foot and more. With the new 

 rains in springtime, they return to the surface and again find their 

 way on to the grass. Furthermore, below a certain temperature the 

 larvae cease their activity and remain dormant. A temperature of 

 10° C. arrests their activity, hence this activity in winter cannot be 

 great. 



There are thus two important facts to be noted, viz. : (1) The 

 longevity of the larvae in the veld, and (2) their absence from the 

 grass during the winter. Based on these two facts a method of sheep 

 rearing could be arranged by which lambs would escape the nodular 

 worm infection and incidentally the infection of any worm with an 

 identical life-history. It would be wise to begin by cleaning a piece of 

 pasture (preferably one fenced in) of the infection, by simply keeping 

 the sheep away for at least one year, preferably longer ; probably 

 fifteen months will be sufficient. This piece of pasture could be 

 utilized for the grazing of cattle. Cattle do not harbour the nodular 

 worm and hence would not maintain the infection. Cattle, however, 

 harbour wireworms, and this fact must be borne in mind. Into this 

 cleaned area no old sheep should be allowed to enter, as with their 

 faeces they would spread the eggs of the nodular worms and in due . 

 time the ground would be infected again. The ewes must lamb out- 

 side the clean area, but, of course, not during the period when the 

 larvae can infect the lambs, i.e. not during the spring or summer. 

 The lambing season must be arranged for during the winter when the 

 infection is at a minimum or absent. It is the experience of many 

 sheep farmers that winter lambs do well where summer lambs will not 

 thrive, and when the ewes at the end of the summer are in good con- 

 dition and winter grazing is good no fear need be entertained about 

 rearing lambs. In order to escape the infection arising out of the 

 spring rains the lambs should be weaned about that time and then 

 placed into the clean paddocks until they have reached an age when. 

 the sheep will stand the infection better. This age is not less than 

 one year. In applying this measure systematically and in a definite^ 

 rotation a sheep farmer should be able to clean his whole farni of the 

 infection, or at least reduce it to a minimum. The lambs in the clean 

 paddocks should be treated for wireworms in case cattle have been 

 grazing there, and also because other parasites, such as tapeworm, will 

 still be present. The M'ireworm remedy is recommended for this pur- 

 pose. Until he has obtained a clean paddock a farmer cannot entirely 

 protect liis sheep from the nodular worm infection, but he can reduce 

 the danger considerably. The infection is only present in moist places 

 and on wet grass, accordingly ho should not allow the sheep to graze 

 on such places, but should water them from a place with a dry 

 approach ; he should not allow them into the pasture before the dew 

 has dried up, and during rainy days he should keep them on the 

 highest ground he possibly can find. Where a farmer grows crops for 

 his sheep he should arrange his feeding so that the sheep receive their 

 supplementary rations at such times, when otherwise they should sub- 

 sist on wet grass and so take up the infection. Winter feeding may 

 also be arranged for, but if green crops, from irrigated lands, are 

 intended to be fed to lambs, tbev should onlv be cut when no moisture 



