PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 29 



'drainage causes weakening of the bushes, we know that weakening of 

 the bushes may cause red spider. By improving the drainage we have 

 been able to get rid of the red spider. I can give you one instance, 

 which perhaps takes us outside the realm of entomology, but which, 

 since it is a case in which control of a pest was efifected, is important. 

 I was once called into a garden in South Sylhet where they had put out 

 some young tea, and for some reason it was badly attacked by red 

 spider. Now, there was no red spider on the bushes round it, and yet 

 there was no apparent reason why the pest should have chosen this area 

 in preference to the surrounding areas. During this particular season 

 ■there had been very wet weather, and an excessive rainfall for that part 

 of the world. Now. when rain falls on to the ground it washes the fine 

 particles down into the soil, the result being that a layer of fine particles 

 is formed which holds up moisture, and produces a temporary condition 

 of bad drainage. Such a layer is known as a pan. There was a paii 

 about 6 inches down, which would be probably 4 inches above the bottom 

 of the lowest of the roots of tea of that age. This means that the roots 

 were in a layer of soil from which water could not get away. We there- 

 fore trench-hoed the area to a depfh of 9 inches, to break this jDan and 

 allow the excess moisture to get away through the soil, and the result 

 was entirely successful. By this means we had removed the cause of 

 the susceptibility of the bushes to attack, and the red spider, which 

 had resisted all attempts to remove it by insecticides, was thrown off. 

 Occasionally red spider reappears on this area. When this occurs the 

 manager of the estate puts in a shallow trench-hoe instead in place of 

 an ordinary round of light hoeing, and the pest is thrown off. 



My paper has consisted of a series of disconnected instances, rather 

 than a discussion of the principles of insect control as a whole, because 

 'my activities have been restricted to a small sphere, but I wish to em- 

 phasize that I do not think that one can expect to devise effective means 

 of control except by a thorough acquaintance, not only with the life- 

 history of the insect, but with its relation to the plant attacked in all 

 circumstances, and of the behaviour of the plant under different methods 

 of cultivation, and the nature of its response to environmental condi- 

 tions, and to modifications of existing agricultural practices. 



I should like to thank Mr. Andrews on behalf of the Meetin" for his ^r. Fletcher; 

 very interesting paper which he has given us. I may say that I quite 

 agree with all that he has said. It is an undoubted fact that, before 

 taking up the application of control measures, it is essential to know 

 every single thing we can know about the insect concerned and the crop 

 which it damages. There is one point in the paper about which I should 

 like some further information. Mr. Andrews said that, by giving several 



