Trumpets don't eat living plants, so don't worry there. If you see them on leaves, they'll be munching on something on the leaf.
As mentioned, review your feeding, perhaps a couple if Assassins. They're saleable, or at least very easy to pass on for P&P. Loach and Puffer keepers will take them for snacks.
They're not a problem at all, and are very welcome in my tanks. If you ever need to catch some, pop an overcooked slice of courgette on the bottom and pop back an hour after lights out, should be able to gather quite a few.