PSYCHE. 



A STUDY OF THE CATERPILLARS OF NORTH AMERICAN 

 SWALLOWTAIL BUTTERFLIES.* — I. 



BY SAMUEL H. SCUDDER, CAMBRIDGE, MASS. 



Interesting as are the transforma- 

 tions of a butterfly in the three earlier 

 periods of its life, marked off by such 

 strict lines from one another, the 

 changes which the same insect, under- 

 goes in shape, in color and in clothing 

 in the different stages of caterpillar life 

 alone, are scarcely less surprising. 

 This is true to so marked an extent in 

 the caterpillars of our swallowtails 

 that if in their earliest stages they were 

 only large enough to have all their 

 peculiarities readily seen by the naked 

 eye, more attention would long ago 

 have been given them. It is also im- 

 portant on other grounds. Weismann 

 has mentioned the desirability of study- 

 ing the early stages of these caterpillars 

 in particular, to acquire a knowledge 

 of their phytogeny, and they have 

 formed the subject of an extended but 

 still incomplete paper by Gruber,t 

 somewhat barren in results from its 

 incompleteness, and in some particu- 

 lais from its inaccuracy. The more 



* Reproduced with slight changes from the author's 

 Butterflies of the Eastern United States and Canada, pp. 



complete material now at liand, studied 

 almost entirely from fresh objects, the 

 extraordinary variety among our New 

 England forms, and the curious fact 

 that these cover almost the entire range 

 of variation known among the caterpil- 

 lars of Papilionini the world over lend 

 special interest to such an enquiry. 



I propose in the first place to give 

 for each of the six species of our fauna, 

 each representing a distinct genus, as 

 succinct an account as possible of the 

 several important changes ; next, to 

 summarize from this the leading lines 

 along which the changes have occurred ; 

 and finally to draw from the facts such 

 conclusions as seem admissible. 



The caterpillar of Laertias philenor 

 (Fig. I.) at birth is uniformly cylindri- 

 cal, of a uniform dark brown, covered 

 with several rows of conical warts of 

 nearly uniform size, most of them bear- 

 ing a single bristle, a few, on' the 

 thoracic segments and just above the 

 abdominal legs, more than one. In its 

 second stage the shape and coloring are 

 the same as before, but the clothing of 

 the body is greatly changed, for all the 

 warts bearing- single bristles have dis" 



