Jimmy, you should visit the Butterfly Forum (click here and I'll take you) for good advice for that question.

You can also do a generalized search by typing nectar plants for butterflies into Google. HERE'S a good website found with such a search.

There isn't any best flower, you should aim for a variety. If you are interested in seeing caterpillars, do a search for host plants.

Your location and the type of butterflies that frequent your yard would be important to know,

make sure to tell that to the Butterfly Forum people .

They love butterfly bushes (for some reason) and tall phlox.