The flower and leaf buds on my apple tree are beginning to come out however I notice that many are showing obvious signs of distress. When I pry open the buds, I find tiny quarter-inch long green caterpillars. Have read elsewhere that the infestation can be treated with Bacillus thuringiensis kurstaki (BTK) ... am wondering if anyone on the forum has had success with BTK? If so, when is the best time to apply it? And finally, does it matter that the bacterium will probably not be applied directly on the caterpillars as they are hidden within the leaf/flower buds?