James Audubon gets all the press, but Maria Sibylla Merian could give him a run for the money in the artist/naturalist department. In 1699, she traveled from Amsterdam to Surinam, where she explored the Surinam River and its surrounding rainforest. Along the way, she sketched the local fauna and flora for her masterwork, The Metamorphosis of the Insects of Surinam, published in 1705. She is the subject of a new biography by Kim Todd, Chrysalis, Maria Sibylla Merian and the Secrets of Metamorphosis.
A nice flash gallery of selected plates is available here (the above thumbnail does her work no justice). Learn more about her at the National Museum of Women in the Arts.