?Ants

It may not be the ants eating your plants...they are just visible in the area...it may be night feeders or larvae of moths or flies...I have earwigs which eat holes in the foliage of my plants...if there are pieces cut out of the leaves some bees, wasps and ants do that to store food or for nest building cellulose...if you have slugs or snails you will see irridescent trails of dried slime where ever they travel...Do some detective work before you start in on the ants because some insect pests are deterred by the presence of ants...ants are usually beneficial.. but if you have a plague of them...it doesn't hurt to cull a few nests. Usually borax will do the job...as Marguerite has said...they will take up the borax laced honeydew and take it back to their nests where they feed it to their larvae...it will kill off a whole colony. usually all it takes is a couple of drops on a saucer or tin can lid just be careful of it...with children, pets etc.

It's uncanny that you mention ants, as only a few days ago I found a nest of them (quite smelly things too) in the midst of my campanula, slowly eating away at them and the bark of the vine growing up into the balcony above. Luckily I've managed to get rid of the beasties but I have unfortunately lost quite a bit of my lovely blue waterfall - shall have to see what it will like next May ....