1188 THE BUTTERFLIES OF NEW ENGLAND. 



recorded from Dulutli, at the western end of Lake Superior ; and Mr. 

 David Bruce, who spent three consecutive summers in Colorado and has 

 closely watched all white butterflies on the search for some of the rarer 

 forms, met with P. rapae for the first time in 1886, seeing a dozen speci- 

 mens about Denver between August and October. In this same year it 

 apparently made its first advent into the eastern half of Florida. Enqui- 

 ries of several entomologists residing there, Messrs. Ashmead at Jackson- 

 ville, Hubbard at Crescent City, Mead and Chase in Orange Co., elicited 

 the uniform response that the butterfly had not reached there ; but Dr. 

 J. M. Wheaton of Columbus, Ohio, writes that he obtained a single 

 battered specimen about the first of April, 1886, while on a visit to Jack- 

 sonville. There is probably, therefore, no state in the Union, east of the 

 Rocky Mountains, where itdoes not occur, though it has not been reported, 

 to my knowledge, from Mississippi, Louisiana or Arkansas. It is hardly 

 possible that it has not covered nearly or quite the whole of each, though 

 Mr. R. d'Ailly of Malvern, Arkansas, writes that it has not yet reached 

 that place in the centre of the state. 



If now we examine the map upon which these statements have been 

 represented, we shall be struck, I think, by two or three principal points : 

 1. The more rapid spread of the butterfly, at first, toward the east and 

 southeast until it reached the sea, rather than toward the southwest along 

 the valley of the St. Lawrence. 2. The comparatively small amount of 

 hindrance mountainous and elevated countries seem to have presented in 

 the early part of its career. Indeed, if the first record of its apjiearance in 

 East Tennessee is correct (and we have excellent authority for it) these 

 would seem in the warmer latitudes to have offered a distinct highway for 

 the movements of the army, which the curves for 1874-1877 are meant to 

 show. 3. The favorable influence of colonies on the spread of the pest, 

 with the single exception of that at Omaha. 4. The excessively rapid, 

 forward movement toward the west and southwest as soon as the Valley of 

 the Mississippi is reached ; compare, for instance, the five years' advance 

 from Cincinnati, Ohio, to Lawrence, Kansas, or to Bastrop, Texas, and 

 the otherwise rapid five years from central New York to western Ohio, or 

 to the five years it took to cover the New England states. 5. The 

 natural limit to its southern extension, as shown by the fact that it can 

 hardly maintain itself at Apalachicola and has not pushed its way into the 

 peninsula of Florida beyond, hardly to, Jacksonville, although it has for 

 ten years been within what would elsewhere be not more than a year's 

 flight away. 



No mention has hitherto been made of the opinion of some entomolo- 

 gists, that Pieris rapae is indigenous to the Pacific coast of America, or at 

 least has been known there for fully a quarter of a century and no one 



