National Audubon Society Field Guide to North American Butterflies by Robert Michael Pyle (1981, Paperback)

This is a very informative, quick and easy to use reference guide that has good color pictures and wonderful references to many North American butterflies. Not every one is listed in here but I found many to most are. It has been my field guide since I was a child using it when I was collecting butterflies. Without it, I would be very lost as to what kinds of butterflies are in my area. I also love it's compact size instead of being a big, bulky, hard to carry around study guide. I haven't found it's equal or better yet. I use mine almost every year and I think every household should own a copy. A great family resource tool.