BUTTERFLIES OF THE DISTRICT OF COLUMBIA 191 



Note. — The National Museum contains a female of the form radia- 

 tus taken by D. B. Mackey in Washington on November 10, 1907 

 (pi. 46, figs. 1,2). 



Caterpillar. — The caterpillar of the spicebush swallowtail is called 

 the " mellow bug." It resembles that of the yellow swallowtail but 

 is of a darker green, and behind the conspicuous eye spots on the 

 third segment behind the head there is a pair of buff spots edged with 

 black, which are a little more than half as large as the eye spots in 

 front of them. 



The caterpillar feeds on a number of different plants, but espe- 

 cially on the sassafras and spicebush. 



It is recorded (Insect Life, vol. 5, no. 3, p. 207, January, 1893) 

 that at Falls Church, Va., on November 5, 1892, the caterpillars of 

 this butterfly were exceedingly abundant, being present by hundreds 

 on sassafras bushes, which they were defoliating. This is a very 

 late date for these caterpillars to be feeding. 



Just before changing to the chrysalis the caterpillar shrinks con- 

 siderably and turns a dirty yellow or dull orange. 



Chrysalis. — The chrysalis is easily distinguished from the chrys- 

 alids of our other swallowtails by its smoothness combined with the 

 occurrence of a slight but distinct ridge running the entire length of 

 the body on either side. In color it is either green or mottled gray 

 and brownish. 



PAPILIO TROILUS ILIONEUS Abbot and Smith 

 Florida Spicebush Swaixowtail 



Rarely specimens of the spicebush swallowtail are taken in which 

 the submarginal spots of both wings are much enlarged. Such indi- 

 viduals are in flight conspicuously different from the usual form. A 

 typical example was taken at Cabin John on August 25, 1929, and 

 another, not quite typical, was taken at the same place on August 

 9, 1931. 



These specimens seem to be referable to the subspecies ilioneus 

 of eastern Florida and Georgia, the northern limit of which in the 

 coastal plain has not been determined. 



PAPILIO POLYXENES ASTERIAS Fabricius 



Parsnip Swallowtail 



Plate 40, Figure 2; Plate 41, Figures 1, 2; Plate 42, Figures 1, 2; Plate 43, 

 Figures 1, 2; Plate 44, Figure 1 



Occwrrence. — Common throughout the District and the surround- 

 ing country, showing but little fluctuation in numbers from year to 

 year. 



