Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Handbook for Butterfly Watchers
By Robert Michael Pyle and Sarah Hughes
Houghton Mifflin Harcourt, 1992
ISBN: 978-0395616291
Cite: 278213 with citation markup [cite:278213]
Though older, still an excellent introduction to "butterfly watching". The first edition (hardback) was published in 1982.