Hi, Are you sure the are actually eating your radishes? Ants generally don't eat radishes, but will cover the plants if there are other insects on the plants that they can dine on. Or, if the radishes have split due to too much water, you might get ants on them. Basically, ants aren't a very big problem in gardens, but are often a sign of something else going on. I'd look closely at your radishes and see if those ants might actually be dining on aphids or some other small creatures that are doing the damage to the plants.