BUTTEEFLIES OF THE DISTRICT OF COLUMBIA 173 



spots on the fore wing are more or less connected by a crescent of 

 dark scales thickest in the middle with the convexity outward. 



Remarks. — The cabbage butterfly first appeared in the District in 

 1872. The distribution of this insect in this region, especially its fre- 

 quency in small open areas near woods remote from farms, suggests 

 that here it feeds largely on native, or at least uncultivated, crucifer- 

 ous plants. 



Dr. E. A. Schwartz has found the eggs on Barbarea vulgaris. He 

 says: 



On April 25th, Mr. Smith and myself made an excursion on the Brightwood 

 road near Washington, and, while observing several siiecimens of Anthocharis 

 genutia, Mr. Smith mentioned that Mr. Schonborn had just found the eggs of 

 Anthocharis genutia on two species of Cruciferous plants, one of them being 

 the common Winter Cress {Barbarea vulgaris). As several specimens of this 

 plant were just then in blossom along our road, we went at once to work to 

 examine them. Within a few minutes several butterfly eggs were found at- 

 tached singly to the larger leaves, and more especially to such plants as grew 

 isolated. Upon comparison, however, these eggs proved to be different from 

 those of Anthocharis, and, in short, turned out to be those of the common 

 Pier is rapae. The Winter Cress is not mentioned by Dr. Riley (Rep. of the 

 Comm. of Agric, 1883, p. Ill) among the known food plants of the Imported 

 Cabbage Butterfly, and also in Europe the same plant is not known to be 

 attacked by this species. At least Kaltenbach does not mention it as such. 



Pieris rapae — as is well known — is one of our earliest buttei'flies, appearing 

 in the vicinity of Washington toward the end of March. As there are no 

 cabbage plants in the fields thus early in the season, it appears highly probable 

 that the first annual generation of Pieris larvae normally subsists on some wild 

 plant, and this common Winter Cress will no doubt be found to be the principal 

 food plant of this species, though it cannot be asserted that it is the only food 

 plant thus early in the season. 



NOTE 



In addition to the species of Pierinae considered in the preceding 

 pages, the following might be expected to occur in the District : 



Zerene caesonia (see p. 251). I Anthocharis olympia (see p. 252). 



Pieris virginiensis (see p. 251). I 



Subfamily Papilioninae 

 Genus PAPILIO Linnaeus 



KEY TO THE SPECIES OF THE GENUS PAPILIO 



a.\ White or greenish white with broad dark-brown bands and a 

 scarlet spot at the anal angle ; tails very long and slender 

 with straight slowly converging sides (pi. 48, figs. 1, 2; 



pi. 49, figs. 1, 2) marcellus (p. 197). 



c^ Color not white and dark brown ; tails shorter and broader, 

 spatulate. 

 h^. Undersurface of the wings chiefly yellow. 

 (f^. Upper surface of the wings yellow with a broad black bor- 

 der including submarginal lunules or broad dashes; fore 



