rKOCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 41? 



all species of Diatrcsa, Chilo and Scirpophaga, and they are present 

 througliout the period of activity of the borers. No Dipterous parasite 

 has been observed in Northern India although some were obtained 

 from Chilo simplex caterpillars sent from Gujarat and the Konkan. 

 Occasionally Carabid grubs (species of Cklwnius) are observed preying 

 upon the larvae in affected stems. But the combined influence of all 

 these enemies does not seem to be great. 



Conclusion. 



The borer pests of gramineous crops of only one locality, viz., Pusa, 

 have so far been investigated. Although most of them are wide-spread 

 there are some which are apparently confined to particular localities. 

 For instance, Diatrwa sp. (C. S. 1610) is confined to Eastern Bengal 

 and Assam. As of all the borers it is the most injurious to grown-up 

 canes, its introduction to other localities should be guarded against. 

 Further work may reveal the presence of other borers in particular 

 localities whose indiscriminate spread may not be desirable. The 

 presence of one such borer is suspected in Southern India. 



In the present incomplete state of the investigation no practical 

 effective measures can be suggested against the borers. The old recom- 

 mendation of cutting out " dead hearts" in sugarcane is of hardly any 

 use and is distinctly injurious under certain conditions especially when 

 the crop is young. Similarly cutting out dry ears of rice has hardly 

 any effect on the crop. We are not yet in a position to suggest any- 

 thing. The presence or absence of alternative foodplants has certainly 

 some effect on the prevalence in any crop of the Pyralid and Noctuid 

 borers. This, as already stated, has been definitely observed in the 

 case of Scirpophaga and the Noctuid borer C. S. 1666. The presence 

 of alternative foodplants has a great deal to do with the absence of 

 Chilo simplex, Diatrcea venosata and Sesamia spp. in injurious numbers 

 at Pusa although each of them is capable of doing serious harm. A 

 good deal of work is necessary in order to be able to study this question 

 thoroughly under different conditions and to regulate alternative food- 

 plants as an effective weapon to fight the borers, if it is proved that 

 control can be effected in this way. 



While we cannot suggest any treatment of the young crop of sugar- 

 cane, in the case of those insects which attack grown-up canes such as 

 Scirpophaga spp. and Diatrcea sp. (C. S. 1610) removal of the affected 

 stems is expected to reduce their number or at least prevent, the increase 

 of their number and hence this practice can be followed in the absence 

 of a better method of dealing with them. 



