INSTITUTE, PUSA, FOR 1919-20 75 



A third point which requires working out is the effect 

 of the presence or absence of alternative foodplanK 

 Instances have been given in the preliminary paper on Cane- 

 borers of such effect in the cases of Scirpophaga and the 

 Noctuid larva (C. S. 1666) in sugarcane and of Chilo 

 simplex in rice. A notable instance which came under 

 observation this year was the occurrence of Diatrwa 

 venosata as a regular pest in sugarcane at Cuttack, where 

 no juar (Andropogon Sorghum) is grown and hardly any 

 Saccharum, spontaneum is present. At Pusa D. venosata 

 occurs very commonly in S. spontaneum and in juar but 

 rarely in .sugarcane. 



As a first step in dealing with the control of the borer 

 pests of sugarcane we must take into consideration (1) the 

 suitability or otherwise of the cane itself to the climatic 

 conditions of the locality where it is grown, (2) the habits of 

 the cane, especially its capacity for tillering during the 

 early stages of its growth, as varieties which tiller well 

 show much greater immunity than those in which tillering 

 is poor, (3) the drought-resisting qualities of the canes, 

 especially in the case of tracts where irrigation is not 

 practised, (4) the natural immunity of the canes against 

 pests and diseases, (5) the effect of the presence and absence 

 of alternative foodplants of the different borers, as well as 

 (6) the discrimination and life-histories (in the fullest sense 

 of the word) of the borers themselves. All the above points 

 are not applicable to any one particular locality, as condi- 

 tions vary locally, but they clearly indicate the need for a 

 whole-time worker, to devote his attention to sugarcane 

 pests only. In order to arrive at successful results in the 

 control of these pests he should include the whole of India 

 within the sphere of his observation and experiment. In 

 my suggestions for expansion of entomological work in 

 India I have already pointed out the necessity for one whole- 

 time expert to work at the question of borers and, when it 

 is realized that a loss of ten per cent, of this crop (and this 

 is probably not an excessive figure for India as a whole) 

 means an annual loss of about three hundred millions of 



