11-t Indian Economic Entomology. [Vol. I. 



seem to represent, not unfairly, the hopeless view taken by the plant- 

 ing community upon the subject. The introduction of a practical remedy 

 is therefore a matter of great importance, and if kerosine emulsion turns 

 out to be as successful as the experiments with it seem to promise, a 

 pratical remedy has at last been found. 



In the case of 285 acres of coffee upon which kerosine emulsion has 

 been employed by Mr. W. Jackson of Ceylon (see his letter below) the 

 pest has been successfully kept down at a total cost of about ten rupees 

 eight annas per acre per annum (including about three rupees per acre 

 spent upon lime that was used as manure to strengthen the plants), at which 

 cost it is estimated that it pays to adopt the treatment. 1 Mr. Jackson 

 found that while coffee that was treated with the insecticide was cleared 

 of the pest, equally good coffee, growing close by and well manured, but 

 not treated with insecticide, was so much damaged by the pest that it 

 utterly failed to keep its condition or to ripen its crop. The plan adopted 

 was to rub over the affected parts of each plant with a piece of cloth 

 soaked in the emulsion, the work being done by coolies. This is ob- 

 viously a most tedious process, and experience of American Entomolo- 

 gists 2 in Florida has shown that by far the most effective method of 

 applying the insecticide is by spraying it in a cloud of fine spray by 

 means of force pumps and spray nozzles. Out of a total of about seven 

 rupees eight annas actually spent upon the insecticide treatment per acre, 

 the cost of the emulsion used by Mr. Jackson amounted to only about 

 eight annas per acre, while the labour of applying it cost about seven 

 rupees per acre ; labour is therefore by far the heaviest item, and as there 

 is every probability that the labour will be materially lessened by the use 

 of force pumps and spray nozzles, it is anticipated that the present cost 

 of the treatment will be much reduced. 



1 Mr. Jackson has since written : " Just a line as regards the cost which I gave you for 

 the kerosine emulsion. I see you have reduced my figures to so much per acre, and this, 

 without some explanation, might he misleading. I started with the ohject that it should 

 be a case of 'hands off' with the hug all through the good coffee, and I simply give, in 

 response to your call, just what it cost us to do this sufficiently to help the coffee to hear 

 the crop then upon the trees, which was a good one, and to keep up as much as possible 

 its condition and prevent the bug spreading. I should say that, perhaps, two thirds 

 of the total acreage, more or less, was affected by the bug in all stages, and the balance had 

 little or none at all, and that only the affected trees were operated upon; the others were 

 passed over and small gangs of coolies kept to watch for any after attaek. If all the coffee 

 had been badly attacked with bug it would have cost much more than it did, and again the 

 work done easily in the season when the young bug is more easily removed will cost less 

 than when done later on, &c. Of course, those who, like ourselves, have carried on this 

 treatment — and there are of course a number who have done so (and no doubt with equal 

 results under similar circumstances) — would understand why total cost was given over all 

 coffee fixed upon to be kept clean, &c." — (Ceylon Observer, 26th June 1889.) 



% Notnbly Messrs. Eiley and Hubbard. 



