HOW TO KNOW THE BUTTERFLIES 



faded straw-yellow beneath, with a very broad black outer 

 margin, in which there is a row of yellow spots. On the fore 

 wings there are four black bars, extending back from the 

 costa ; the inner one of these crosses the hind wings also. 

 This species is represented by both sexes, and is found in 

 nearly all parts of the United States and Canada. 



(2) The Glaucus Form, Papilio glaiuus glaitcus (Plate VI, 

 Fig. 2.) — In this form the disk of the wings is entirely black, 

 but the black bands of the Turnus form are faintly indicated, 

 especially on the lower surface, by a darker shade. The 

 marginal row of yellow spots is present, and also the orange 

 spots and blue scales of the hind wings. This form is repre- 

 sented only by the female sex, and occurs only in the more 

 southern part of the range of the species, i. e., from Delaware 

 to Montana and southward. In this region both yellow and 

 black females have been reared from eggs produced by a 

 single female. 



Caterpillar. — Enlarged at the third thoracic segment and 

 about two inches long when fully grown. In color it is deep 

 green, and the enlarged thoracic segment bears on each side a 

 large greenish-yellow spot edged with black enclosing a black 

 streak above and having a pupil of blue bordered with black. 

 The hind edge of the first segment of the abdomen is banded 

 with yellow and the front edge of the next segment is banded 

 with black. 



Food-plant. — Birch, poplar, ash, wild cherry, fruit trees, 

 and many other trees and shrubs. 



The tiger swallow-tail disports itself on its 

 great yellow wings from the Atlantic to the 

 Pacific and from Canada to the Gulf of Mexico. 



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