Genus Pieris 
The species ranges from Oregon to central California, and 
eastward to Colorado. 
(3) Pieris occidentalis, Reakirt, Plate XXXIV, Fig. 13, 6 
(The Western White). 
Butterfly. —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 II, 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, 6 . 
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, 6 
(The California White). 
Butterfly .—Smaller in size than the preceding species, with 
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