1914.] NATURAL SCIENCES OF PHILADELPHIA. 165 



of skilled chemists and its well-equipped laboratories, and with two 

 abundant species — Danaida {Anosia) plexippus feeding on Asclepiads 

 and Pharmacophagus (Papilio) philenor feeding on Aristolochias — 

 by which to test the validity of Haase's hypothesis. 



3. Indirect Evidence that Pharmacophagus philenor is a 

 Model possessing Distasteful Qualities. 



I have myself only seen this insect alive on one or two occasions, 

 and have certainly never had the opportunity of observing it in 

 relation to its natural enemies, nor do I know of any such observa- 

 tions. Scudder states (6, 1248-9) that the larvae are gregarious 

 when young and semigregarious in later life, that the perfect insect 

 is very tenacious of life, and he quotes Edwards for the observation 

 that it has a strong and disagreeable scent. These qualities, espe- 

 cially the two latter, are generallj^ characteristic of distasteful species; 

 but Skinner states (32, p. 124) that later specially directed observa- 

 tions have failed to confirm Edwards. Skinner also records (p. 125) 

 the fact that the larvae are attacked by parasites, but this is commonly 

 true of Danaince, Acrceince, and other distasteful much-mimicked 

 groups. Haase is, so far as I am aware, the only writer on the 

 subject who has supposed that the immunity of models is complete, 

 and probably in all cases protection from insectivorous vertebrates 

 is to a large extent balanced by exceptional exposure to the attacks 

 of parasites and certain other insect enemies, such as Asilid flies and 

 Hemiptera (19). 



I quite agree with Skinner (p. 125) that the principal attacks are 

 made during the earlier stages of an insect's life — and think of the 

 elaborate protective adaptations which are common in these stages — 

 yet I do not doubt that the imago is subject to severe persecution 

 from enemies of many kinds. Furthermore, it must be remembered 

 that each imago, the heir of all the other stages, and especially each 

 female, is of far greater value to the species than a single pupa or 

 larva and often hundreds of times as valuable as an ovum. 



Although I must admit that there is no direct evidence to prove 

 that P. philenor is nauseous- to birds (p. 123), I believe that much 

 might be learned if American naturalists would offer large numbers 

 of this swallo^vtail to many species of insectivorous birds in confine- 

 ment, offering at the same time other butterflies with a procryptic 

 under-surface, such as Vanessa milberti or species of Grapta (Eugonia). 

 The North American Danaine models might be tested at the same 

 time. Although the records of field observations are greatly to be 



