BUTTERFLIES OF THE DISTRICT OF COLUMBIA 19 



In connection with the fauna of the coastal plain two other but- 

 terflies call for special notice. Neither of these winters over in the 

 District, both of them arriving early in spring from the Chesapeake 

 Bay region or the lower Potomac, living here throughout the sum- 

 mer, and completely dying out during winter. 



The common milkweed butterfly {Danaus plexippus) is always to 

 be found in summer in the District, but it is seldom very common ; 

 it is never the conspicuous element in the fauna here that it is in 

 the fauna of the territory about Chesapeake Bay or about the broad 

 reaches of the lower Potomac. The painted lady {PyraTneis cardu'i) 

 is usually present in the District during summer; it is occasionally 

 abundant, but in some years is wholly absent. 



In the mountains southwest of the District there are several spe- 

 cies which have a more or less extensive range southwestward or 

 westward but do not occur on the Atlantic watershed east of the 

 bases of the mountains. At the present time these scarcely call for 

 consideration in connection with the District fauna, but some of 

 them are common not very far away and are to be looked for as 

 casuals or as temporary residents. 



The District possesses a single butterfly, Poanes massasoit hughi, 

 that is not known from any other region. Two other singularly 

 local skippers occur not far away. Poanes aaroni aaroni is common 

 in the salt marshes of southern New Jersey and has been taken on 

 the eastern shore of Maryland, and A7r1blyscirt.es Carolina is known 

 only from the southeastern to east-central part of North Carolina, 

 and southeastern Virginia. 



In summing up the faunal relations of the District, it may be 

 said that the fauna of the District is for the most part composed 

 of butterflies that range very widely over eastern North America. 

 As the District lies just on the eastern border of the southern exten- 

 sion of the range of many northern species, its fauna includes a 

 number of characteristically northern forms which give it a pre- 

 dominantly northern aspect. Such southern species as extend far 

 northward mostly pass by the District area to the east in the region 

 of the coastal plain, and the few that reach the District are less 

 numerous in individuals and less f aunally diagnostic than the north- 

 ern species. The southern Appalachian species are represented only 

 by casual individuals. 



RELATIVE OCCURRENCE AND HABITATS 



The relative proportions of the several groups of butterflies found 

 in the District are shown in Table 1. For a list of the District 

 butterflies, see Table of Contents, pages v-viii. 



