calscape.org: CNPS database of native plants and associated butterflies and moths (both host and nectar plants). Searchable.
California Plants as Resources for Lepidoptera: a document that lists many moth and butterfly species and their host & nectar plants
BUTTERFLY GARDENING: SELECTED REFERENCES
Arbuckle, Nancy and Cedric Crocker (eds.). 1991. How to Attract Hummingbirds and Butterflies. Ortho Books.
Caldwell, Jeff. Notes on Larval Food Plants of Some Bay Area Butterflies. 3pp.-xeroxed
Garth, John S. and J.W. Tilden. 1986. California Butterflies. Berkeley: University of California Press.
Stewart, Bob. 1997. Common Butterflies of California. Point Reyes Station, CA: West Coast Lady Press.
Stokes, Donald, Lillian Stokes and Ernest Williams. 1991. The Butterfly Book: An Easy Guide to Butterfly Gardening, Identification, and Behavior. Little, Brown and Company.
Tekulsky, Mathew. 1985. The Butterfly Garden. Boston: The Harvard Common Press.
Xerces Society/Smithsonian Institution. 1990. Butterfly Gardening. Sierra Club Books.