We feed birds in the winter. But Americans have not been as aggressive about feeding butterflies in the summer.
The best way, of course, is to supply many varied and native flowers for your area. Plant those with a variety of colors and shapes — bright red and purple flowers rich in nectar in trumpet and cone shapes with sturdy “landing pads” — and you will see butterflies gravitating to your yard from spring through summer. Love the look of nature? Get really saavy and plant the vines and vegetation that caterpillars need also.