126 



NATURE SKETCHES IX TEMPERATE AMERICA 



birds. Nor have I a knowledge of the amount of destruction 

 occasioned by birds to the eggs. But from actual observation I 

 have seen numbers of the pupae and eggs that were parasitized by 

 Hymenoptera. It is in these stages that the butterflies generally 

 suffer the greatest amount of destruction from animal enemies. 



The Monarch is seem- 



ingly much more abundant 



rthan its mimicker. This is 

 one of the special condi- 

 tions under which mimicry 

 exists. The vital period of 

 exposure is in the adult 

 female when she is laden 

 with eggs. At this time 

 she is more exposed than 

 the shorter lived male. 

 Botli the Monarch and the 

 ^'iceroy enjoy freedom from 

 attacks by predaceous birds 

 and lizards at this time. 

 On the whole, althougli 

 there are features of the 

 life of tiiese butterflies not 

 understood, the proof of 

 mimicry is as obvious as 

 it is in the usual run of 

 these cases, yet there is a 

 more })lausible explanation 

 on the ground of natural selection in accounting for it than 

 there is in the })urcly chemical theory of coloring witliout 

 definite use to the animal pos.sessing such colors. 



Poulton • lias recently asserted that the Monarch butterfly, 

 which is the old world ancestor of the Danaine butterfly, invaded 

 the new world by way of the north at a time sufficiently remote 

 to permit of the acquisition of generic distinction. The Monarch 

 was mimicked by an indigenous species of Limenitis, closely 

 similar to and probably identical with the banded purple 

 L. arihenii.^, which thus originated the Viceroy. 



' Trans. Entomological Society of London, 1908, p. 487. 



The Viccroii Pupa after fran.ifnrming 

 from the eater pillar .shoini in the pre- 

 ceding plate. It.s queer form of body 

 and color is highly protective. 



