20 



BULLETIN 15 7, U. S. NATIONAL MUSEUM 



Taki.b 1. — Relative occurrence of families and subfamilies of butterflies in the 



District of Columbia 



Group 



Number of 

 species 



Per cent 



Nymphalidae 



Satyrinae 



Nymphalinae. 



Danainae 



Libytheinae... 



Lycaenidae - 



Qerydinae 



Lycaeninae . . . 

 Theclinae 



Papilionidae 



Pierinae 



Papiliomnae.. 



Hesperiidae 



Pyrginae 



Hesperiinae... 



Total. 



26 1 28.26 



92 



15.22 



16.30 

 '40."22' 



100. 00 



4.35 



21.74 



1.09 



1.09 



1.09 

 3.26 

 10.87 



8.69 

 7.61 



15.22 

 25.00 



100.00 



Compared with the corresponding figures for all the species of 

 eastern North America, exclusive of the Gulf coast and southern 

 Florida, the Hesperiidae (skippers) are seen to be nearly 10 per cent 

 more numerous (40.2 as against 30.3 per cent) ; the Papilionidae 

 (swallowtails and pierids) are found to be slightly less numerous 

 (16.3 and 17.4 per cent) ; the Lycaenidae (coppers, blues, and hair- 

 streaks) are fewer (15.2' and 20.8 per cent), and the Nymphalidae are 

 also somewhat fewer (28.2 and 31.4 per cent). 



The figures given for the Papilionidae scarcely represent the true 

 conditions. Three species {Pieris 'protodlce^ Pafilio cresphontes, and 

 Papilio inarceUm) have almost completely disappeared; two others 

 are immigrants, one {Pieris rapae) from Europe and the other 

 {Colias eurytheme) from the Southwest; and a sixth {Phoebis eubule) 

 is only a casual visitor. Subtracting the two immigrants and the 

 casual visitor, the number of Papilionidae in the District is reduced 

 to 12, and the percentage to 13, which is considerably less than the 

 normal (17.4 per cent). 



The marked preponderance of skippers, especially when taken 

 in connection with the fact that several species which should occur 

 here have not as yet been reported, suggests that the present fauna 

 of the District is one from which various elements have disappeared 

 through the clearing of the land and resultant changes. Changes 

 in conditions arising from the clearing of the land affect skippers 

 less than they do other butterflies, because of their small size 

 and also because of the fact that all of them in this general region 

 feed either on grasses or on other very common plants. 



The 92 species and subspecies of butterflies known from the 

 District may be classified as follows according to residence : 



