BUTTERFLIES OF THE DISTRICT OF COLUMBIA 179 



In the South it is occasionally destructive to young orange trees. 



Chrysalis. — The chrysalis has the surface strongly rugose; the 

 anterior half of the body is bent upward at a considerable angle, the 

 ventral profile being a rather abrupt rounded angle. It resembles 

 most closely the chrysalis of Papilio polyxenes, but it is larger, with 

 the ventral profile much more strongly bent, and there is a promi- 

 nent compressed tubercle at the base of the antennae, which is lacking 

 in the chrysalis of the parsnip swallowtail. 



PAPILIO GLAUCUS GLAUCUS Linnaeus 



Yellow Swallowtail 



Plate 33, Figures 1, 2; Plate 34, Figures 1, 2; Plate 35, Figure 1; Plate 36, 

 Figure 1 ; Plate 37, Figures 1, 2 ; Plate 38, Figures 1, 2 ; Plate 39, Figures 

 1, 2 ; Plate 40, Figure 1 



Occwrrence. — Common, though not abundant, throughout the Dis- 

 trict and the surrounding country, the numbers fluctuating but little 

 from 3^ear to year. 



This butterfly frequents especially the drier open deciduous woods, 

 the borders of woodlands, and orchards, from which it wanders into 

 gardens, and when an abundance of red clover, thistles, milkweed, or 

 other flowers serves to tempt it, it strays more or less widely out over 

 open fields. It is, however, essentially a woodland species, finding 

 its proper home in glades, along the sides of roads, and about the 

 banks of rapid streams, and in open country the individuals, espe- 

 cially the females, are always more numerous near the borders of 

 the woods than elsewhere. 



Habits. — The yellow swallowtail usually flies high, from 10 to 20 

 or more feet above the ground, Avith a leisurely, though rather rapid, 

 flight, often meandering irregularly about, turning from side to side, 

 now rising several feet, now coming down again, flapping and sail- 

 ing. In open glades, along the banks of streams, and on the borders 

 of woodlands it plays about, flying leisurely up and down, from the 

 tops of the trees nearly to the ground and up again. When traveling 

 over clover fields it keeps close to the grass tops, coursing about and 

 occasionally turning to the right or left. In open country the con- 

 trast between the actions of this butterfly and the rapid, nervous, and 

 irregular flight of the parsnip swallowtail is very striking. It has 

 been remarked that especially early in the morning, and also after 

 rains, the yellow swallowtail is fond of sunning itself on leaves with 

 its wings extended almost to the horizontal and held at right angles 

 to the sun's rays. 



It is exceedingly fond of flowers, and from early in spring, when 

 the lilac and syringa are in bloom, to late in autumn it is one of the 

 most frequent and conspicuous visitors to gardens. In summer it 

 feeds especially on elder, clover, butterflyweed, and milkweed, later 



