12 Indian Museum Notes. [Vol. VI. 



plucked, long ago made by Mr. Wood-Mason, has precisely the 

 opposite effect to that desired, and rendered the bush more suscep- 

 tible to further attack.* 



The conclusion appeared to be that the likely means of dealing 

 with the insect was one of prevention rather than of cure, and involved 

 making the bushes after pruning into as unfavourable a condition 

 as possible for laying eggs, for a long enough time to prevent the 

 insects then in existence laying eggs on the tea at all, and at the same 

 time by a process of suffocation preventing the eggs already in the 

 bushes hatching out at all. It is obvious that for a fair test of such a 

 method, when one has to deal with a flying insect, it was absolutely 

 necessary to experiment on a plot of tea sufficiently isolated to 

 prevent the entrance of outside sources of infection. This cannot 

 usually be done, but fortunately there is a means of knowing fairly ex- 

 actly the nature of the attack in the early season, that is to say, whether 

 it is caused by freshly introduced insects, or by those bred in the 

 bushes, by the position of the punctured leaves. The insects bred in 

 the bushes almost always produce small punctures caused by the 

 young insects in the interior of the bushes ; while the freshly intro- 

 duced bugs produce in greater part large punctures chiefly caused by 

 adult insects, and are near the surf ace of the bush, After the end 

 of May this distinction does not really hold good to an extent which 

 will enable the attack to be classified. 



The materials tried up to the present in these experiments are (i) 

 kerosene emulsion, made up according to the American formula and 

 diluted to ten times its volume, though I usually, however, have to 

 employ for the waters in the tea districts, 2 lbs. of soft soap per two 

 gallons of kerosene to get a satisfactory emulsion easily ; and (2) 

 Chiswick compound, employed as recommended by the Chiswick 

 Soap Company at the rate of 25 lbs. to two hundred gallons of 

 water. A Gould's Standard Sprayer has been employed throughout. 



In the experiments in 1902, the area treated was twelve acres 

 quite isolated by being a 100 yards from any other tea. This dis- 

 tance, as had been already seen in May, was not, however, sufficient 

 to prevent the introduction of insects from the nearest outside plots 

 of tea. The tea was pruned two years back in February, but no 

 cleaning out of the twiggy growth was attempted, as this is not 

 usually done in the Terai where this experiment was carried out. 

 The spraying was done with the kerosene emulsion in March, and 

 with the Chiswick compound in April. In May I visited the garden 

 and found that very few (2 per cent.) of the bushes on either of the 

 treated plots were even touched with the pest, and, moreover, that 

 * Mr. Green, in Ceylon, has a'so noted this fact- 



