Butterflies and Moths of North America
An easy map search on the Butterflies and Moths of North America Web site lets you click on states for a list of species seen in that state, along with descriptions and photos. There's also a taxonomy list to help you sort through families and subfamilies with such charming monikers as brushfoots, swallowtails, skippers, and gossamer-wings.
Authors Thomas J. Allen, Jim P. Brock, and Jeffrey Glassberg provide an incredibly comprehensive guide to help gardeners and enthusiasts determine what caterpillar they're looking at. Caterpillars in the Field and Garden: A Field Guide to the Butterfly Caterpillars of North America features over 900 color photographs, showcasing one adult butterfly and five caterpillars per page, so you can compare differences in related species. Each entry includes a range map, identifying marks, habitat, where and when it is most likely found, and host plants. Common names are provided for host plants, with an index cross-referencing scientific names and butterflies attracted to each plant. Helpful introductory material describes families and subfamilies, explains the insect's four life stages, and discusses conservation efforts as well as raising a caterpillar -- what a delightful project for a child!