^/ 



PAPILIO III., IV., V. 



in company with them, the black Timms is in a way protected. I think this 

 snfficiently accounts for the scarcity at any time of the yellow females in this 

 region (West Virginia). Papilio PhUenor has a strong and disagreeable scent, 

 and it has been suggested by Mr. Mead, that this rendering it distasteful to 

 birds would serve to protect other black species flying with it. 



How then does it happen that at the southeast, in Georgia and Florida, the 

 yellow females should strike so experienced an observer as Mr. Morrison as being 

 quite as plenty as the black ; the very opposite to the conclusion reached in Illi- 

 nois and Kansas and Texas, by other experienced observers ! That Mr. Mor- 

 rison should consider the yellow fully as abundant as the black, leads me to 

 believe that in reality they are much more so, and that in those districts they 

 outnumber the black largely; for imless a collector is especially searching for 

 them, their resemblance to the males would often cause them to be overlooked. 

 Indeed, at a moderate distance one could not be distinguished from the other. 

 The western region is largely prairie. It may well happen there that the con- 

 stant elimination of the yellow form has in the course of time overcome anv 

 remaining tendency of the black to produce yellow females, for every black now 

 flying must be supposed to be descended from many generations of black, with 

 a yellow one in the line only at rare intervals, perhaps in not more than one 

 generation out of a hundred. I can see how it is, that at the southeast, the 

 repression of the yellow female by enemies may be greatly diminished, owing 

 to the more wooded country, the greater moisture of the climate, milder tem- 

 perature, and the excessive luxuriance of all insect life, whereby there is no 

 reason why one species only should be singled out as a special object of prey. 

 The conditions are essentially diflerent from those which prevail on the drv 

 and exposed western plains. Moreover, the peril caused by the bright color 

 and slow flight of the yellow female Turmcs, must be much lessened by its 

 constantly associating with other species of Papilio, similarly colored, such as 

 Ci'esphontes and Palamedes, larger and gayer than itself In fact it is the yellow 

 female 2\irmis which is here protected, and so it should not merely hold its own, 

 but really be able to prevail against its sister form. It occurred to me whether 

 it might not also be a fact that the insectivorous birds were more largely repre- 

 sented in the west than on the Atlantic seaboard, so that all species of butterfly 

 might be more subject to destruction in the former regions, and I wrote Professor 

 Baird for information on this point. In reply I have a statement from Mr. Rob- 

 ert Ridgway to the following eftect : " A larger proportion perhaps of the birds 

 belonging to the semi-prairie districts west of the Mississippi belong to the in- 

 sectivorous sei'ies than is the case with those inhabiting the Atlantic seaboard. 

 Thus, taking the Tyrannidfe, for example, which are preeminently fly-catchers, 



