I need some help while I can still save my hardy hibiscus plant. I have just noticed that a couple of the leaves have a small, thin, greenish worm/caterpillar eating from the underside. I'd like to know what it might be & what is the best way to get rid of them. I've squashed a few, but would rather use a home remedy spray, if possible. As far as I know, they're only on this plant. I don't have a picture to show, but if it's necessary, I might be able to get one.