OF WASHINGTON, VOLUME XIII, 1911. 3 



Atlantic coast and gradually diffuse themselves inland, fol- 

 lowing, as I have indicated in the paper to which 1 have pre- 

 viously alluded, certain regular lines of progress. There are, 

 however, a number of a species which occur inland that give 

 no indication whatever of having been introduced through any 

 of the seaports of eastern or, indeed, western United States. 

 One of these is the now well-known To. \optera grain in nm, 

 which has spread generally over the United States west 

 of a line drawn from northeastern Ohio approximately to 

 Philadelphia, Pennsylvania. We have almost been able to 

 trace the dispersion of this species in the Red River Valley of 

 the North. While it occurs along the Mexican border from 

 Brownsville, Texas, to the Imperial Valley of Southern Cali- 

 fornia, in only one instance has it been reported throughout 

 the territory northeast of the line to which I have just alluded. 

 Mr. Hay hurst reports its occurrence in the vicinity of Bos- 

 ton, but no one else, with the most careful search, has been 

 able to find it either in New York, New England, or New 

 Jersey; only in southern Pennsylvania. It has not yet be- 

 come destructive in the East to any extent north of the Caro- 

 linas, while in the West its ravages have extended as far north 

 as Chicago and Omaha. Besides this, although Texas was 

 one of the later States to be brought under cultivation, this 

 pest began its ravages as early in that State as elsewhere in 

 the country. 



With the present information we have there is far more 

 probability of its having been introduced into and made its 

 way northward through Mexico into the southwestern por- 

 tion of the country than there is of its having been imported 

 into any of the coastal seaports. 



Another case in point is that of Meromyza praloruni, a 

 European species which during the last few years has been 

 discovered in the mountainous regions from Mexico north- 

 ward into northern Montana, Idaho, and Washington, and it 

 now turns out that what has been going under the name of 

 Meromyza americana is only a lowland form of the European 

 species. As we find this also all along the Mexican border, 

 it affords another illustration of a probable Mexican or Cen- 

 tral American origin. 



When we call to mind the more recent natural diffusions of 

 two Mexican species, whose spread has been actually observed, 

 viz, Murgtintia histrionica and Anthonomus grandis t we find 

 a great similarity between their known diffusion over the 

 country and the apparent diffusion of the two species Toxap- 

 tera graminum and Meromvza pratorutn. 



