PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 

 Vol.90 Washington: 1941 No. 3118 



NOTES ON SOME NORTH AND MIDDLE AMERICAN 

 DANAID BUTTERFLIES 



By Austin H. Clark 



Among the mosi interesting problems connected with tlie study of 

 the Lepidoptera are those having to do more or less directly Avitli the 

 migrations of many species, and "of all the migratory species the one 

 that has attracted the most attention is our common milkweed butterfly, 

 or monarch {Danau-s 'plexifpus). 



This butterfly ranges from far north in Canada southward through- 

 out North and South America to Patagonia. It occurs in a number 

 of different forms, of which only the most northern (plexippus) and 

 the most southern (erippus) are known to be migratory, the several 

 tropical forms being apparently' sedentary and in some cases of very 

 restricted range. 



All the forms of this butterfly are nnich alike. But if we are to 

 obtain a clear picture of the migrations of our common North American 

 form {plexippus) and its distribution, regular or casual, in Central 

 America and in the West Indies we must distinguish it from the local 

 and apparently sedentary' forms, the ranges of which it frequently 

 overlaps and with some of which it intergrades. 



Dr. William Schaus and John F. G. Clarke have been so kind as 

 to permit me to study the excellent series of specimens of this species 

 in the collection of the National Museum, including the Barnes collec- 

 tion. In addition to these I have studied several hundred individuals 

 mainly from New England and from the vicinity of Washington, D. C, 

 in my own collection; about 70 specimens from the vicinity of New 

 Orleans, La., generously sent me by Percy Viosca, Jr. ; a fine specimen 



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