Well, yeah, there is a way during the day, too...but unfortunately, it's not too much better. Turns out if you hang a werewolf, they will revert back to their "natural" form. In towns where this has been tried, it has had mixed success. Frequently, towns are able to erradicate their werewolf problem using this method.
Unfortunately, if it turns out that the "werewolf" isn't a werewolf after all, it's not such a joyious occassion.
I will say that in all cases I've ever seen, the werewolves will usually continue feeding each night until they become extinct or until they have no more food and have to move on. So doing nothing isn't a great choice, either.