Answer: It's really important to identify exactly what is eating your plants before attempting to spray something on them. You may do more harm than good. My friend the entomologist is an "ant expert" and she says there are only a couple species of ants that actually eat plants. The more likely scenario is the ants are interested in the other insects on your plants. Ants "herd" aphids, protecting them from predators in exchange for honeydew, the sweet excrement the aphids produce. It'll be obvious if this is the case in your garden - you'll see ants on plant stems and leaves and clusters of pale green/brown soft-bodied aphids nearby. You can control either ants/aphids them by blasting them off the plants with a strong spray of water. You might need to do this daily, making sure you get underneath and between leaves where the aphids may be lurking.
I always start with the simplest method first, and if that isn't successful, move on from there. The insecticidal soaps are made from plant-derived fatty acids and target soft-bodied insects. There's really no way you can target the bad guys without fallout on the good guys. If you can regularly monitor and tolerate some damage to your plants, over time Mother Nature strikes a balance, with the beneficials coming in to control the bad guys. Healthy vigorous plants will withstand insect attacks best, and it's really the best thing you can do to provent insect problems.
Ladybugs and their larvae are voracious eaters of aphids, which often attack veggies. They often "arrive" a week or two after the aphids, so not spraying with chemicals is a good idea if you'd like to attract them to your garden to consume aphids for you. Check your plants out carefully (you may even need a magnifying glass) to see who's doing the munching. Good luck!
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