220 Zoology of Colorado 



in this and occidentalis continuous. (A common species 

 of the Eastern States, extending into Colorado; it has 

 been taken on the University of Colorado campus) .... 

 Pieris protodicc Boisduval and Leconte. 



Pieris napi is a common Old World species, represented in 

 North America by various forms which have received names. 

 Four of these have been reported from Colorado. Peculiar dwarf 

 females of P. protodice, with the anterior wings 1 9 mm. long, and 

 the hind wings beneath very heavily marked, were taken by C. F. 

 Leach in the foothills about seven miles west of Sedalia. The 

 first was seen as early as February 12, and it is to be presumed 

 that the cool weather influenced the size. The Colorado form of 

 Euchloe ausonides has received the names color adensis Henry 

 Edwards and montana Verity, but there is little to distinguish it. 

 Eurymus scudderi has the females white or pale yellow, the latter 

 form being called flavotincta Cockerell. Our most interesting 

 Pierid butterfly is Eurymus (or Colias) eurytheme, the larva of 

 which feeds on alfalfa, clover and related plants. This species 

 is polymorphic, and appears also to be imperfectly differentiated 

 from the common sulphur butterfly of the Eastern States, Eurymus 

 philodice. Formerly, the matter appeared perfectly simple; there 

 was a yellow species in the East, and an orange one in the West. 

 Both produced white females from time to time, exactly as in 

 related European species. However, in 1876, W. H. Edwards 

 described a yellow form, which he called eriphyle, from British 

 Columbia. In 1883 he set forth still another yellow type, called 

 hageni; this he had from Pueblo, Colorado. Later researches 

 indicated that eriphyle and hageni were practically the same thing, 

 and Edwards proved by breeding that this was a form of the 

 orange E. eurytheme. Late in the fall, and in greater numbers 

 early in the spring, there occurs the form autumnalis Cockerell, 

 smaller, with narrower dark borders, and the hind wings beneath 

 grayish green. This is probably a direct result of the cooler 

 weather, and not a genetically distinct form. These eriphyle 

 forms are exceedingly similar to the E. philodice of the Eastern 

 States and since philodice has been spreading westward, it be- 

 comes difficult to decide the exact status of some specimens. 

 E. philodice is on the whole a clearer yellow, with blacker borders, 

 especially those of the hind wings of the female. 



