INFLUENCE OF CLIMATE 41 



PJven where this does not happen, there may be a reduc- 

 tion in the crop brought about by the reduced vitahty of 

 the plants. 



The crowding of the bugs on the tender leaves, for 

 which there is a marked preference, also affects the plant 

 at one of its most vital parts. The indirect effect of the 

 sooty mould that invariably grows on the honey dew cover- 

 ing the leaves, as has already been described, may be so 

 serious as to cause the leaves to drop off, though it must 

 be admitted that this rarel}^ happens. 



How far these serious effects are produced depends on 

 the health and vigour of the plant and the conditions 

 under which it is grown. Where a. tree is weak from 

 other causes, the further tax on its strength by the bug 

 often proves fatal. But where it is healthy and vigorous, 

 the effect is largely minimised. Thus we find a very much 

 smaller effect on coffee estates in Mysore than on the ex- 

 perimental plants grown in Bangalore, where the conditions 

 are much more unfavourable. 



Influence of Climatic Conditions. 



The pest is most to be feared in years when the North- 

 East monsoon is scanty and a long period of dry weather 

 succeeds it. This occurred in 1913 and 1914, with the 

 result that the pest increased at an alarmingly rapid rate. 



The course of the pest varies considerably through 

 the seasons in Mysore. It is difficult to detect the pest 

 in infected estates immediately after the South- West mon- 

 soon. With the advent of the dry weather the bugs 

 apparently come out of the shelters in the ants' nests and 

 begin to multiply. There is even then a considerable 

 check on them imposed by the dark fungus which kills 

 a large number during the last quarter of the year and 

 continues to be effective till the hot season if the North- 

 East monsoon is abundant and well distributed. When 

 summer is fairly well advanced, this hindrance is with- 

 drawn and the insects rapidly regain their hold on the 

 plants. The pest is at its worst immediately before the 

 South-West monsoon. When sufficient rains have been 

 received, the white fungus works havoc among them and 

 before the last rains of the South-West monsoon are 

 over, usually more than 90 per cent of the bugs are 



