BUTTERFLIES OF THE DISTRICT OF COLUMBIA 197 



variability in this species is of the same nature as, although much 

 less extreme than, the variability in the allied P. hairdi. In both 

 species the variability shows very considerable geographical varia- 

 tion. Comparable instability in the color pattern is shown in the 

 dark females of the yellow swallowtail {P. glaucus), which also is 

 subject to geographical variation. 



PAPILIO MARCELLUS Boisdnval 



Zebea Swaixowtail 

 Plate 48, Figures 1, 2 ; Plate 49, Figures 1, 2 



Occurrence. — Formerly abundant, but now local and not common. 

 It is found in some numbers early in spring in the open woods along 

 the canal from Cabin John to Great Falls, and in summer it occurs 

 both in the woods and in the adjacent open fields, but in lesser num- 

 bers. In summer it is an occasional visitor to gardens in George- 

 town, Cleveland Park, Chevy Chase, Silver Spring, and elsewhere 

 in the immediate vicinity of Washington. Late in summer it be- 

 comes very scarce. 



It is abundant in many localities not far from the District both 

 in Maryland and in Virginia. 



This is a butterfly primarily of unkept fields grown up to brush, 

 of bushy pastures, and of open woods with more or less extensive 

 clearings. In the District and immediately adjacent areas recent 

 improvements have almost completely done away with this type of 

 country, resulting in a great decrease in the numbers of this butterfly. 



The Schonborn collection includes 13 specimens dated April 8, 10, 

 and 25, 1882, June 8, 11, and 13, and September 12, 13, and 16, 1885, 

 two pupae, and one pupal skin labeled as having given forth the 

 butterfly September 4, 1881. 



Mr. Shoemaker has specimens taken in spring, in July, and in 

 September. 



Habits. — Early in spring the zebra swallowtail is seen coursing 

 through the woods with a swift and direct flight, the wings in con- 

 stant rapid motion, 3 or 4 feet above the ground. It is very shy and 

 dodges from its course at the least alarm. It is very fond of flowers, 

 especially of those of various blueberries, and will even feed on such 

 as are not more than 3 or 4 inches from the ground and more or less 

 concealed by leaves, searching them out somewhat after the manner 

 of the cybele {Ai^gynnis cybele). 



The large summer individuals are in their habits quite different 

 from their smaller parents. Their flight is more leisurely, less 

 hurried, and less nervous with less rapid wing beats, and they wander 

 more or less from side to side, sailing from time to time. They stray 

 widely over fields and gardens and are often to be seen sailing about 

 over muddy spots or sitting on the mud with their wings half raised. 



