BUTTEBFLIES OF THE DISTRICT OP COLUMBIA 



25 



GENERAL FEATURES OF THE DISTRICT FAUNA 



Perhaps the most characteristic feature of this area is the great 

 abundance of large swallowtails. Especially late in summer these 

 conspicuous insects attract the attention of even the most casual 

 observer. It was probably this feature that led some of the early 

 writers who mentioned the natural history of this region to remark 

 particularly on the number and beauty of the butterflies. As these 

 writers came from England, where there is only a single rather small 

 native swallowtail {Papilio macliaon hritt aniens) ^ which has a 

 restricted range and is not very common, with a second, the " scarce 

 swallowtail" {Papilio podaUHus), as a casual visitor from Europe, 

 they would naturally be amazed at the abundance and variety of these 

 insects here. 



But broadly speaking the District and the surrounding country is 

 a poor region for butterflies. Few kinds are really abundant, and a 

 number are very local, being found only in a few widely separated 

 stations or only in a single place. 



I know of no other region where butterflies are so scarce in spring 

 as they are in the District and in its immediate vicinit3^ The mor- 

 tality during the winter months is here evidently considerably in 

 excess of what it is elsewhere. The reason for this is probably to be 

 found in the alternate freezing and thawing during winter, the 

 severe cold waves which occur almost every winter, and the severe 

 hot spells characteristic of spring. 



The scarcity of many species in spring, however, is due not so 

 much to the fewness of the individuals as to the fact that the 

 emergence of the spring brood is much prolonged and extends over a 

 period of several weeks, so that only a small proportion of the total 

 number of spring individuals is on the Aving at any one time. Else- 

 where, particularly in the north, the individuals of the spring brood 

 of these same butterflies all emerge within a relatively short time, 

 so that the species appear to be much more common than they 

 are here. 



In the following lists the local butterflies are classified on the 

 basis of their relative abundance. Those butterflies are listed as 

 abundant of which more than 15 may be taken in an average day's 

 collecting; common butterflies are those of which from 6 to 15 may 

 usually be taken in a day; frequent butterflies are those which can 

 always be found, but of which an average of less than 6 will be taken 

 in a day ; and rare butterflies are such as are taken not more than once 

 or twice in a season. 



ABUNDANT 



Junonia la/i>i7iia (occasionally). 

 Pyrameis cardui (occasionally). 

 Phyciodes tharos. 



Danaus plexippus (occasionally). 

 Everes comyntas. 

 Eurema lisa. 



