72 BUTTERFLIES 



growing. Open groves, the borders of woods, and the 

 margins of streams or marshes are the places where one is 

 most likely to find spice bush and sassafras. These are 

 the places to look for these butterflies which one may often 

 see in graceful flight near the ground, pausing now and 

 then to seek a sassafras leaf or to sip the nectar from a 

 flower. 



The Tiger Swallowtail 



Papilio glaucus 



One of the many things that make a study of the life- 

 histories of butterflies of great interest is the variations in 

 the development of many of the species. One who follows 

 the simplest life-story of a butterfly and sees the egg 

 change to larva and the larva change in size and form and 

 color with each successive moult and then change again 

 into the seemingly inert chrysalis, from which there finally 

 comes the winged butterfly — unlike the egg, unlike the 

 larva, unlike the chrysalis — a creature of perfect beauty, 

 wonderfully adapted to living freely in the air and sipping 

 ambrosial nectar from the flowers — one who follows these 

 changes with awakened vision can scarcely fail to have a 

 sense of wonder as to the laws that govern such intricate 

 phenomena. But the marvel is still more pronounced in 

 the case of those butterflies which have two or more forms 

 arising from the same lot of eggs in a way which science 

 has as yet not adequately explained. 



The splendid Tiger Swallowtail is an example of this 

 dimorphism which is of especial interest because of the 

 fact that the extra form is confined to one sex and to only 

 a part of the geographical area over which the butterfly is 



