BUTTERFLIES OF VIRGINIA 



By AUSTIN H. CLARK 

 Curator, Division of Echinoderms, U. S. National Museum 



Life is always changing, never static. So in considering the butter- 

 flies of Virginia it is necessary to note the changes that take place 

 from year to year — changes in abundance, in range, and in form. 

 Some butterflies are disappearing from regions where once they 

 were common. Others are increasing in numbers. Still others from 

 time to time have entered the State from more or less distant regions 

 and have made themselves thoroughly at home. 



Two such recent immigrants are now perhaps the commonest and 

 most generally distributed species in Virginia. It is possible that they 

 are exceeded in actual numbers by two small and inconspicuous 

 ones, the pearl-crescent (Phyciodes their os) and the tailed blue 

 (Everes coiiiyiitas) ; but if not the most numerous of Virginia butter- 

 flies they are certainly the most conspicuous. One of these is the 

 cabbage white (Pier is rctpae) of Europe which was first noticed about 

 1870 in Surry County, and the other is the orange clover butterfly 

 (Colias philodice cnrythenie) that entered the State from the west 

 and south about 20 years ago (figs. 60, b; 61, a, b) . 



The orange clover butterfly was wholly unknown in Virginia prior 

 to 1920, when Dr. Frank Morton Jones captured one on the Dela- 

 ware-Maryland-Virginia peninsula. By 1923 it was common as far 

 north as Wachapreague on the Eastern Shore, where it had replaced 

 the native yellow clover butterfly (Colias philodice philodice) (fig. 

 60, a) and to the north it occurred as far as Berlin, Md. In 1925 it 

 was found in the Dismal Swamp, though there were still no records 

 farther west. However, by 1929 it was abundant in the west as far 

 north as Lexington, occurring in lesser numbers farther north, and 

 it was also common in the Kanawha and other valleys in West 

 Virginia where previously it had been unknown. Since then it has 

 swept over the entire State (fig. 59), where it is now thoroughly 

 established everywhere except only in the highest mountain pastures 

 where its yellow eastern relative still is common. 



With the increase in numbers of this intruder the numbers of its 

 native yellow relative diminished. Now this yellow butterfly, which 

 20 years ago was the commonest and most conspicuous butterfly of 

 Virginia's fields and pastures, has in most regions almost disappeared. 



