Digging round the plant where they are disturbs their runs and does much good. At the same time they should be brushed off any part of the tree they have attacked, and the tree should be well shaken.
All this, however, only does temporary good, for they often are found as thick as ever on the plant a week later.
Tobacco water is beneficial, but in wet weather it is soon washed off.
Kerosene oil is very efficient. A little is put round the stem, but it is expensive. The next best thing I know is the earth oil (petroleum) from Burmah, and this is cheap enough. It is thick, but used from a bottle it gets heated by the sun and is then quite limpid.
When white ants are found on a tree, a little with a small brush is put on the part they have attacked. They are also well shaken off, and a ring of oil is placed round the stem. My experience is that they will not attack that tree again for a long time. I was at first fearful that both it and the kerosene (the one, I believe, is only a manufacture of the other) would injure the trees, but both are safe. I strongly recommend others to try it, if they doubt, on a small spot only in the first instance.
Whatever is used, or whatever is done, white ants must not be left to work their will in the autumn. All the trees should then be examined once at least, and once again, if possible, the following spring.
Blight (a serious matter, I hear, in Cachar) I know but little of. I do not remember hearing anything about it when I was there, now some fourteen years ago. It is rare in the Chittagong district, but I have seen one or two trees attacked with it. Under its influence the young leaves get covered with brown spots and shrivel. It is most destructive to the yield of a garden.
From one or two experiments made I believe pruning off all the diseased branches, and scraping back the soil for a space of 2 feet round the stem, so as almost to lay the roots bare, will be found beneficial, but I do not speak with certainty.
All the Himalayan gardens are free from these three pests detailed, except that occasionally a few crickets have been seen.