PAPILIO III., IV., V. 
in company with them, the black Turnus is in a way protected. I think this 
sufficiently accounts for the scarcity at any time of the yellow females in this 
region (West Virginia). Papilio Philenor 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 unless 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 any 
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 different from those which prevail on the dry 
and exposed western plains. Moreover, the peril caused by the bright color 
and slow flight of the yellow female Turnus, must be much lessened by its 
constantly associating with other species of Papilio, similarly colored, such as 
Cresphontes and Palamedes, larger and gayer than itself. In fact it is the yellow 
female Turnus 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 effect: u A larger proportion perhaps of the birds 
belonging to the semi-prairie districts west of the Mississippi belong to the in¬ 
sectivorous series than is the case with those inhabiting the Atlantic seaboard. 
Thus, taking the Tyrannidae, for example, which are preeminently fly-catchers, 
