Answer: I wonder if they are butterflies rather than moths? They sound like Dryas julia. Whether they are moths or butterflies, the adults are simply drinking nectar from your plants. They are not eating the the plants so they're not causing any damage. However, they may be laying eggs. If so, when the eggs hatch, the larvae will feed on the leaves. I would just leave them alone and simply appreciate them. If you don't want the next generation to feed on your plants, you can use Bt (sold as Dipel or Thuricide) on your plants when the larvae appear.
Good luck with your garden.
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