Small White or Cabbage Moth?

We've been seeing a lot of the little white butterflies the back yard recently; so far they seem to prefer the catnip, which is now blossoming all over the place, but Cindy wants to keep them from laying eggs on the tomato plants.

We had always called these butterflies Cabbage Moths, but now it appears they are really called Cabbage Whites, or even Small Whites, since they really are butterflies, not moths.

Cindy's keeping a vigilant eye on them, whatever you call them; we're trying to encourage all the butterflies to go to the butterfly garden in the front yard, instead of the vegetable garden in the back.  Their caterpillars are welcome to chew up all the Asclepia and Buddleia they want, but stay off the veggies.