It is similar to the West Coast Lady as they both have many small dots on the underside of the hind wing. The west coast lady has an orange spot along with the white ones on the edge of the upper fore wing. The American Painted Lady has two very large eye spots on the underside of the hind wing.
The Painted Lady butterfly eats mainly Cirsium spp. In California, California Thistle, Cirsium californicum, and Red Thistle, Cirsium proteanum are common. White forget-me-not, Cryptantha spp., and Fiddle-neck, Amsinkia spp. are also eaten to a lesser degree. Mallow, Malva spp. and Stinging Nettle, Urtica spp. are also eaten but not as much so.