Sorry about the unusual title....I just couldn't think of a more precise description at the moment. I have a 4-month old Siamese bamboo which has just begun growing new culms, one of which is now as high as my second-storey window. One day, I looked out at the new shoots and realized that the leaves at the tips had been webbed together into some sort of coccoon. At first, I thought it was the work of friendly spiders and left the problem alone. But today, I unravelled one of them and found a green caterpillar inside (at least, that's what I think it is). They don't seem to be doing much physical damage to the leaves, but it does prevent the new shoots from opening and growing, and is rather unsightly. Could this be some sort of bamboo-specific pest or a general garden-variety one, and what should I do about it? Thanks.

P.S. My climate is tropical rainforest.