I did have ants on my peppers for awhile. They didn't seem to really be causing any harm. I'd see them scurrying around the lips of the pots and shit just running about like they were up to no good, but never saw any problems. I finally got rid of them by spraying pesticide around the door to my closet since that's the only way in and out. No more ants in the grow room. Now they're just in the kitchen and the living room, but fuck those places.