122 MIMICRY IN BOREAL AMERICAN RHOPALOCERA. 



most of his references are cited from Gentry (11). The observations made by 

 Gentry were unreliable and probably nearly all fictitious. W. L. McAtee (2), 

 an authority on this subject, says in reference to the work by Gentry, "but with 

 regard to the bird food, it is certain that the only safe course is to regard them as 

 almost entirely products of the author's imagination." Marshall has given 

 numerous records from other parts of the world to sustain his contention. 



Evidence of a negative character is not of overwhelming value but it cer- 

 tainly has its place, and should stimulate exact observation. Marshall states 

 that "they (the opponents of the theory) unite in condemning the theories of 

 mimicry on the ground that they involve too many assumptions for which there 

 is no experimental evidence . ' ' In regard to the relations between birds and insects 

 so far as this fauna is concerned, the case may be stated somewhat differently. 

 Before the theory is accepted it will be necessary to have sufficient evidence to 

 reasonably prove the hypotheses advanced by the advocates of Batesian and 

 Mullerian mimicry. Packard (7) could only find records of four species of North 

 American butterflies being eaten by birds: Argynnis myrina, Vanessa milherti, 

 and Pieris rapoe. He says it is evident that for temperate North America and 

 for Europe the evidence is entirely too slight to even suggest the theory; the 

 attacks of birds are a negligible factor. 



G. L. Bates (1) who spent six years investigating the stomach contents of 

 birds of the South Cameroons, Africa, found Coleoptera in 213 stomachs and 

 Orthoptera in 177, but no butterflies. 



Dr. Philip P. Calvert, a distinguished neuropterist and careful field observer 

 and collector, spent a year in Costa Rica and although he particularly looked for 

 evidence of birds attacking butterflies, he did not see a single instance of it. 



The literature on this subject so far as this particular fauna is concerned is 

 meager. W. H. Edwards (10) says he believes that Papilio turnus was often 

 destroyed by owls at night. Dr. Scudder mentions having seen a tr alius which 

 he inferred had been eaten by a bird. 



W. G. Wright (6), a collector of great experience, says during twenty-five 

 years' collecting on the Pacific coast of the United States he never saw but one 

 attempt of a bird to catch a butterfly and the attempt ended in failure. I have 

 asked the following well known entomologists and field workers whether they 

 have ever seen birds attack and eat the bodies of butterflies: E. T. Cresson, E. T. 

 Cresson, Jr., J. A. G. Rehn, Morgan Hebard, Frank Haimbach, H. A. Wenzel. 

 They all replied in the negative. Hebard and Rehn have collected extensively 

 in almost every part of the United States. Mr. Witmer Stone, a well known 

 ornithologist, has not seen birds eat butterflies. The writer has collected American 

 butterflies for forty-three years and has never seen a butterfly eaten by a bird. 

 For the present it therefore seems fair to assume that the evidence of mimicry 

 in this respect is very far from being convincing. . 



Papilio philenor, the so-called pharmacophagus model, generally feeds, ro 

 the larval stage, on some species of Aristolochia . 



