176 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



until the middle of September, when it is very abundant in certain 

 localities, and then decreasing, although individuals are seen on the 

 wing until late in October if the weather remains warm. Unusually 

 large examples of both sexes are not infrequent late in summer. 



The individuals emerging toward the end of June show the sum- 

 mer type of coloration. 



In the District this swallowtail appears to hibernate only as a 

 pupa, as none but fresh individuals are found early in spring. 



The scarcity of this insect in spring, in striking contrast to its 

 abundance in autumn, indicates an exceptionally heavy mortality 

 during winter. It should be noticed that the second brood does not 

 appear until more than a month later than the second brood of the 

 other local swallowtails, and the individuals of the second brood 

 do not become abundant until it is too late for their progeny to 

 reach the pupal stage before winter. It may well be that the very 

 small size and the scarcity of the individuals of the spring brood 

 mean that only those individuals which, as caterpillars not yet quite 

 fully grown, are in a condition to pupate with the coming of the 

 cold weather are able to survive, the overwhelming majority of the 

 individuals — adults and young caterpillars — being killed off each 

 autumn. 



Sirring form. — Early-spring individuals (pi. 62, figs. 4 and 6) 

 are ahvays very small, having the fore wing about 40 mm. long. In 

 contrast to all our other local swallowtails except P. niarcellus^ both 

 sexes appear at the same time, and both sexes are of the same size. 



A male in the National Museum collected by William Middleton 

 at Falls Church, Va., on April 28, 1915, is typical of the spring form. 

 The fore Aving is 43 mm. long. The hair on the body is very long, 

 giving the insect a shaggy appearance, and there is a tuft of long 

 hair on the frons. The whitish spots on the wings are enlarged, 

 resembling those of the summer females, and the color is dull, being 

 scarcely brighter than in the brightest summer females. 



A female captured at Great Falls on May 9, 1931, has the fore 

 wings 40 mm. long. It is clothed with long hairs, like the male just 

 described, and the white spots are enlarged. 



The hind wings of spring individuals are more rounded than the 

 hind wings of the individuals of the summer brood, and the tails are 

 relatively shorter. 



The two spring specimens noted, and others examined, agree per- 

 fectly in every particular with specimens of the Californian P. 

 philenor hirsutus., and if that form is to be recognized they must be 

 referred to it. This case is somewhat similar to that of Argynnis 

 apJwodite ciprls^ which occurs as a definite geographical form in 

 Utah, Colorado, and New Mexico, and is also found in eastern Massa- 



