I have a bay tree in a pot and in general it is in good health. However, it regularly suffers from the depredations of the caterpillar of an unidentified moth. The caterpillar causes the leaves to curl up upon themselves whilst it eats holes in the leaves themselves. Occasionally it attacks the bud tips. When searching for these, if disturbed they attempt to escape by dropping quickly from the leaf, but still attached by a silken thread. The caterpillars are small and bright green, and form small (5-10 mm) cocoons. They don't appear to do any severe damage to the bush but they leave unsightly holes in the leaves, or damage growing buds. Any advice on what they might be and how to control would be appreciated.