I ran across the website while searching for some info on caterpillars and their camouflage. The text is The Life of the Caterpillar by J. Henri Fabre (copr. 1916). It's very detailed, but he was a good writer (and the translator, too). You can tell the man must have had a good sense of humor from his descriptions of some things. I didn't read all of it, but bookmarked it to read bit by bit later. Enjoy! http://www.eldritchpress.org/jhf/cater.html
Some vintage reading about caterpillars
