MIMICRY IN BOREAL AMERICAN RHOPALOCERA. 125 



None of the butterflies mentioned by Packard as being attacked by birds 

 feed on poisonous plants. We do have some butterflies that feed on plants 

 that are called medicinal. Terias nicippe feeds on Cassia marylandica, wild 

 senna. Melitcea phaeton larva feeds on Chelone glabra, balmony. Papilio mar- 

 cellus (ajax) feeds on the paw-paw, Asimina triloba. Wild senna and balmony 

 act as cathartics in the human economy and paw-paw is used by medical men 

 of doubtful character. The principal enemies of the species of Papilio are not 

 those that prey on the imago but those inimical to the egg, larva, and chrysalis. 

 The eggs are destroyed by hymenopterous parasites, ants, spiders, crickets, and 

 other insects. The larvae are attacked by a number of hymenopterous and 

 dipterous parasites and the chrysalids are destroyed by numerous enemies, such 

 as squirrels, mice, lizards, birds. 



There is little reason to believe that the stages of philenor are more immune 

 to the attacks of enemies than the other species. Aaron found a colony of the 

 larvae on the moon vine. They were badly parasitized. The early stages have 

 not been reared or studied as frequently as the other three species. While it is 

 true that the butterfly is abundant in some places it is rare in the communities 

 where there are entomologists. This is due to the fact that the food plants have 

 become scarce, owing to being articles of commerce. In the northern States 

 Aristolochia sipho is not a common plant but is only occasionally used as an 

 ornamental vine. Philenor is rare in the vicinity of Philadelphia. I have seen 

 the species abundant in the mountains of North Carolina, the specimens being 

 unusually large. It is difficult to understand and interpret the laws of nature, 

 and nature may do curious things, but if these species are subjected to so many 

 risks in the three early stages why should they have a doubtful kind of protection 

 in the imago form? Probably the answer would be that it is necessary to 

 protect the female of the species as she has eggs to deposit and her death would 

 mean the destruction of many individuals in an early stage of existence. 



The three species, glaucus, asterius, and troilus, do bear a resemblance to 

 philenor but this happens in any aggregation of species in a genus. They look 

 alike to the human eye but birds may be able to differentiate them. They do 

 not deceive the trained eye of the naturalist if he gets within a reasonable dis- 

 tance of them whilst they are on the wing. 



The females of these species all differ more or less in appearance from their re- 

 spective males. Scudder used the word antigeny to define these secondary sexual 

 characters or differences. These differences occur in numerous species and it 

 seems logical to consider that they are governed by a general law rather than that 

 a few of them are caused by protective resemblance. The model species philenor 

 is also antigenetic. Why should this be if antigeny is brought about by resem- 

 blance or natural selection? Surely we cannot account for the differences of 

 appearance in the sexes of the model on the ground of protection. Professor 

 Poulton says the three mimics, glaucus, asterius, and troilus, acting as secondary 

 models, produced an effect on Limenitis arthemis and that the result of this 



