PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 27 



lime-sulphurs can be traced to the presence or absence of suspended 

 matter. Thus in spraying for red spider with lime-sulphur it is not 

 advisable to filter away all the suspended matter, and the lime-sulphur 

 concentrates on the market will therefore sometimes fail when a home- 

 made mixture will succeed. This is again a question of detail, which 

 may make all the difference between success and failure, and which 

 could be easily overlooked by one not thoroughly conversant with the 

 behaviour of the pest. There was one other case in which spraying was- 

 effective, but I cannot tell you much about that because it was a pro- 

 prietary insecticide made in Switzerland and I never knew the composi- 

 tion of it. This was an insecticide which we used against Thrips (Physo- 

 thnps setiventris, Bagn., and Haplothrips ienuipennis, Bagn.) in 

 Darjiling. Spraying is often said to be useless in Darjiling because 

 of the amount of rain, but we found that Thrips could be sprayed: 

 with this substance during fine periods with success. 



Tea is grown mainly for the young shoots, and we find that in the 

 case of most of our insect pests the young shoots are damaged by the 

 insecticide at a weaker concentration than is necessary to kill the insect, 

 which, of course, puts spraying out of the question, and here the import- 

 ance of knowing all about the plant comes in. 



Spraying is of course one of the mechanical methods of control. The 

 methods of control which have given the best results in my experience 

 are cultural methods of control. You all know what I mean by cultural 

 methods of control. They consist of adaptations of existing agricultural 

 practices to meet the necessities which are brought into existence by 

 the presence of the insect pest. You yourselves advocate such methods 

 in the case of many pests, as for instance digging up the stimips of plants 

 after the crop has been removed, in the case of cane-borers, etc., and 

 such recommendations come under cultural methods of control. Now 

 in tea we have had successes by the application of these methods, much 

 more success in fact than in any other way, but if such methods are to 

 be successfully worked out the investigator must possess not only an 

 intimate knowledge of the insect he is dealing with, but also an intimate 

 knowledge of the plant that is being dealt with, of all practices followed 

 in connection with its cultivation, etc., and of the way in which the plant 

 responds to different treatments. 



Termites occur all over the tea-districts, and do a great deal of 

 damage to tea. We have tried fumigation, we have tried insecticides 

 in the soil, we have tried deterrents of one sort or another, and all with- 

 out success. Sometime ago I spent a short time in South Sylhet in- 

 vestigating white ants and their behaviour in tea. I found, after examin- 

 ing a large number of bushes, that the white ants always get into the- 



