Genus Piens 



The species ranges from Oregon to central California, and 

 eastward to Colorado. 



(3) Pieris occidentalis, Reakirt, Plate XXXI V, Fig. 13, 6 

 (The Western White). 



Biitterjiy. — Not unlike the preceding species on the upper 

 side, but easily distinguished by the markings of the under side 

 of the wings, which are not concentrated in blotches, but extend 

 as broad longitudinal rays on either side of the veins from the base 

 to the outer margin. 



Early Stages. — These require further investigation. We do 

 not, as yet, know much about them. 



The species has a wide range in the mountain States of the 

 West, where it replaces the Eastern P. protodice, 



(4) Pieris protodice, Boisduval and Leconte, Plate XXXIV, 

 Fig. 10, $, ; Fig. 11, ? ; Plate 11, Fig. 7, larva; Plate V, Figs. 66, 

 67, chrysalis (see also p. 12, Fig. 26) (The Common White). 



Butterfly. — Allied to the foregoing species, especially to P. 

 occidentalis; but it may always be quickly distinguished by the 

 pure, immaculate white color of the hind wings of the male on 

 the under side, and by the fact that in the female the hind wings 

 are more lightly marked along the veins by gray-green. 



Winter form vernalis, Edwards, Plate XXXIV, Fig. 18, 5. 

 What has been said of the typical or summer form does not hold 

 true of this winter form, which emerges from chrysalids which 

 have withstood the cold from autumn until spring. The butter- 

 flies emerging from these are generally dwarfed in size, and in 

 the males have the dark spots on the upper side of the wings al- 

 most obsolete or greatly reduced, and the dark markings along the 

 veins on the under side well developed, as in P. occidentalis. 

 The females, on the contrary, show little reduction in the size 

 and intensity of any of the spots, but rather a deepening of color, 

 except in occasional instances. 



Early Stages. — The life-history of this insect has often been 

 described. The caterpillar feeds upon cruciferous plants, like 

 many of its congeners. 



It ranges from the Atlantic to the Rocky Mountains, from 

 Canada to the Gulf States. 



(5) Pieris sisymbri, Boisduval, Plate XXXIV, Fig. 12, $ 

 (The California White). 



Butterfly. — Smaller in size than the preceding species, with 



278 



