DISTRIBUTION 337 



[ersey. In general, the mountains of Central America and Mexico and 

 :he plateau of Mexico have been barriers to the northward spread of 

 many species, which have reached the United States by passing to the 

 east or to the west of these barriers, in the former case skirting the Gulf 

 of Mexico and spreading northward along the Mississippi valley or along 

 the Atlantic coast, in the latter event traveling along the Pacific coast 

 to California and other Western states. Not a few species, however, 

 have made their way from the Mexican plateau into New Mexico and 

 Arizona ; this is true of many Sphingidae. The butterfly A nosia berenice 

 ranges from South America into New Mexico, Arizona and Colorado; 

 while many of the Libytheidae have entered Arizona and neighboring 

 states from Mexico. The chrysomelid genus Diabrotica is almost ex- 

 clusively confined to the western hemisphere and its home is clearly in 

 South America, where no fewer than 367 species are found. About 100 

 species occur in Venezuela and Colombia, "of which n extend into 

 Guatemala, 8 into Mexico, and i into the United States." We have 18 

 species of Diabrotica, almost all of which can be traced back to Mexico, 

 and several of them as the common D. longicornis to Central 

 America. "The common Dynastes tityus occurs from Brazil through 

 Central America and Mexico, and in the United States from Texas to 

 Illinois and east to southern New York and New England." Erebus 

 odor a ranges from Ecuador and Brazil to Colorado, Illinois, Ohio, New 

 England and into Canada, though it is not known to breed in North 

 America, being in fact a rare visitor in our northern states. 



Southeast. Many South American species have made their way 

 into southern and western Florida by way of the West Indies, while 

 some subtropical species have reached Florida probably by following 

 around the Gulf coast. The semi tropical insect fauna of southern and 

 southwestern Florida, including about 300 specimens of Coleoptera, 

 according to Schwarz, is entirely of West Indian and Central American 

 origin, the species having been introduced with their food plants, chiefly 

 by the Gulf Stream, but also by flight, as in the case of Sphingidae. 

 Ninety-five species of Hemiptera collected in extreme southern Florida 

 by Schwarz and studied by Uhler are distinctly Central American and 

 West Indian in their affinities. Indeed Uhler is inclined to believe that 

 the principal portion of the Hemiptera of the United States has been 

 derived from the region of Central America and Mexico. 



Eastern. On the Atlantic coast are many European species of 

 insects which have arrived through the agency of man. Most of them 

 have not as yet passed the Appalachian mountain system, but some 

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