The last brood of caterpillars, however, change to chrysalids which do not disclose the butterflies until the following spring. And then the first that come out are the Marcellus form and the last the Telamonides form. So we may have these two forms maturing from the same brood of autumn caterpillars. This seems a sufficiently complicated life-history to suit the most persistent solver of puzzle problems, but there is an additional factor which adds much to the possible confusion of the broods. In each brood of caterpillars from the earliest to the latest there are a certain number of chrysalids which remain dormant through the remainder of the season and the following winter, maturing into butterflies the next spring. Consequently at the end of every winter there are a miscellaneous lot of chrysalids which represent every brood of caterpillars that lived the previous season, and all of these develop into either Marcellus or Telamonides butterflies. Such a condition of affairs certainly represents what an old New Englander would be likely to call a "mixed-up mess," and it is difficult for science to find rhyme or reason to explain it. It speaks eloquently for the perseverance of W. H. Edwards that he was able with infinite patience through years of study and experiment to untangle this intricate web of butterfly existence. While the preferred food plant of this species is papaw, the caterpillars are also known to feed upon the spice bush and upland huckleberry. When full grown these caterpillars are about two inches long and of a general pea-green color, banded transversely with yellow and black, and having an especially conspicuous band of this sort on the third ring behind the head. The scent organs are protruded when the larva is disturbed and emit an offensive odor. The chrysalids are green or brown according to the surroundings. The Zebra Swallowtail is a southern butterfly found as far west as Texas and the Rocky Mountains and having its northern limits in a zone ranging approximately from Massachusetts to Nebraska. It is especially abundant in the Southern states east of the Mississippi River. Mr. S. F. Denton found this species abundant in southern Ohio where the females laid their eggs upon the small papaw bushes. They selected the leaves of these bushes for sleeping quarters, "clinging to the under side of the leaves where early in the morning they might be taken with the fingers." _Other Swallowtails_