no they wont. ants are preditor animals. they dont eat plants. well at least around here. infact they are prob good for them because they will ward off any wannabe plant eater. they are considered a beneficial insect so keep them. u wanna hear something really crazy. there are a few tropical ants that cut leaves (called leaf cutter ants) that take the leaves and bury them in the ground..the leaves then get all moldy cuz they lick it and shit...and they feed the mushrooms to their babies. so they are into shroomin also
I saw a plant in texas last year that had an ant nest inside the stalk. Don't know if it harmed the plant or not.
they have been known to pick at your plants, and at the very least , tend the aphids that suck the juice out of plant life. but it shouldn't be too much of a problem. i guess it reALLy depends on where you live and the indiginous ant population. keep all aunts away, they are absolutely devistating to your plants and stash. one minute it is there, the next it is gone or destroyed.