INSTITUTE, PUSA, FOR 1916-17 77 



The points to note are the following : — 



(1) The high percentage of damage by Red Rot. 



(2) In the Purple Mauritius plot all affected plants 



had been cut out once in April and again in 

 May. Still the amount of damage due to 

 insects in June was greater than in any of the 

 other plots. It is probable that Purple Mauri- 

 tius is more liable to damage by insects than 

 the other varieties. In order to test the effect 

 of this treatment of cutting out affected shoots 

 further experiments will be undertaken next 

 3*ear with a single variety. This year's experi- 

 ence however leads us to believe that the only 

 insect which will be amenable to this treatment 

 is Scirpophaga. 

 Now that the other borers can be distinguished and 

 therefore their habits definitely studied, other 

 methods of control will have to be found out by 

 further study and experiment. 



Other insects observed for the first time to feed under 

 ground among sugarcane roots include — 



Alissonotum piceum grubs. 



Alissonotum simile grubs. 



Myllocerus blandas grubs. 



A Melolonthid grub (probably Anomala sp.) has been 



observed definitely to gnaw into sugarcane stems from the 



side, causing a dead heart in the case of young shoots or 



killing the shoots and young plants. The grubs are still 



feeding and have not yet been reared. 



Myllocerus discolor grubs have been found commonly 



among sugarcane roots. 



The search for Coleopterous larvae among sugarcane 



roots has been continued and several Chrysomelid and 



weevil grubs have been found which are still feeding at the 



time of writing this report. 



As reported last year, termites have been observed to 



cause more damage to new shoots than to setts. Further 



observation confirms the view that it is only in particular 



f2 



