Hi! Welcome to the world of butterflies. Like many of us, you might become addicted to planting for the butterflies.

We have a FAQ section that has a great list of nectar plants and just as important, if not more important, a list of the caterpillar host plants.

Knowing what state or geographical region you are in is also helpful. You can be a zone 5/6 on the west coast as well as the east coast, but the butterflies can be very different.

If I attract butterflies will that also create a problem in my veg garden? Also conversely, if I plant my butterfly plants in one area will that attract the nuisance caterpillars and their parent butterflys?

There are very few butterfly caterpillars that are a nuisance - I doubt that even giant swallowtail caterpillars present much of a problem for citrus growers, since they spread their eggs out.
The only common vegetable I know of that gets cats is tomatoes - and peppers, to a lesser extent - and tomato hornworms (which make a sphinx moth) will find your tomatoes regardless of whether you plant butterfly plants, meaning both host and nectar plants.
Butterflies are very plant specific, and drawing butterflies to your yard will not cause them to lay eggs on vegetables/plants that they're not programmed to use.
The only other leps I can think of that might lay eggs on your vegetables would be generalist moths, but you could get them just as easily without planting a butterfly garden.
I've got tomatoes, peppers, squash, and onions in my butterfly garden, they don't have a single pest on them, and I don't spray. So my advice is to go ahead and mix butterfly plants into your veggie garden!
Sherry

I would definitely plant milkweed for monarch cats and fennel and parsley for eastern black swallowtail cats. I also have a butterfly bush, cosmos, blanket flower, asters. I have a gopher that keeps eating my purple cone flowers. I need to get a bigger have-a-heart trap to catch him, though.