FAMILY TYPICAL BUTTERFLIES. 145 



aud it L'speciixlly abounds about vegetable gardens both in 

 countiT and city. It is triple-brooded and hibernates as a 

 chrysalis; the earlier broods appear in any locality where 

 P. oJeracea also occurs, about a week or a little less before 

 that species, but the last brood is apparently contempora- 

 neous. The eggs, which are Florence-flask-sha23ed, taj^er 

 only on the upper third, have about twelve vertical ribs, 

 are pale yelloAV and are laid erect in large numbers, but 

 not in close proximity (except accidentally), on the under 

 surface of leaves; they hatch in about a week. Tlie cater- 

 pillar feeds on a great variety of Cruciferous plants, espe- 

 cially on cabbage (to which it is very destructive, often 

 totally ruining a crop), but also on some other plants and 

 especially mignonette; in cabbages it bores into the heart 

 and fills the passages with its excrement. When not hi- 

 bernating, the chrysalis state lasts ten or twelve days. The 

 male butterfl}^ has a very faint but agreeable odor. . 



Seasonal dimorphism is shown in the heavier markings 

 of the first brood of the season; and a variety sometimes 

 occurs (and was especially prevalent when it was first in- 

 troduced) of a pale canary-yellow throughout. 



Subfamily Swallows-tails. 

 43. Genus Laertias. 



LAERTIAS PHILENOR— THE BLUE SWALLOW-TAIL. 



(Papilio pliileuor.) 



Butterfly. — Upper surface of wings blackish brown with yel- 

 lowish lunules ill the fringe and a submarginal series of pearl-gray 

 spots. Under surface of fore wings nearly the same with larger 

 markings; of hind wings slate-bro\Yn at base, beyond varying 

 from metallic green to blue with seven large premarginnl rounded 

 orange spots;, broadly bordered with black and tipj^ed above 

 with white. Expanse about 4^ inches. 



Caterpillar. — Head black. Body naked, nearly cylindrical, 

 nearly black, with two series of small orange spots on each side, 

 and at both ends of the body, on either side, a series of long black 



