36 THE CANADIAN ENTOMOLOGIST. 



to search for more congenial localities, there becoming attached to new 

 food plants, which, no doubt, have an influence in diversity of colors. We 

 have an instance of this in the American representative of Vanessa 

 aniiopa, which is of rare occurrence in Anticosti ; but where it retains the 

 features of its English congener, while those taken in more southern 

 latitudes assume a different coloration. Instance also the introduction of 

 Pier is rap(B into Canada of late years. This species has now a struggle to 

 exist in the latitude of Quebec, but so long as its food plant is abundant 

 it will continue with us. It has been gradually moving south, where, with 

 a more favorable climate, it propagates extensively. This butterfly also 

 shows the effects of climate in the appearance of a yellow variety. It 

 may be possible that the butterflies called brevieauda by Mr. Saunders and 

 Aiiticostiensis by Mr. H. Strecker, had a similar origin . The connecting 

 link or aftinity of Papilio brevieauda with asterias is only a. perplexing 

 attempt to make the Anticosti form an ally of the continental P. polyxenes^ 

 which is Scudder's new name for asterias.^ 



I cannot find sufficient reason for such connection, as there is quite a 

 distinction between the larva of asterias and that of the Anticosti 

 butterfly. It may, however, be discovered that an affinity occurs in 

 P. asterioides and brnncanda or Aiiticostiensis ; and although the former is 

 found in Mexico, I see no reason to doubt their connection in years gone 

 by.* 



Considering the present rate of travel of Pieris rapae southwardly, it 

 may during the course of another twelve years reach Costa Rica, and 

 there change so much externally as to be claimed as another variety, while 

 the Canadian form will still be called the segregated species. Mr. Her- 

 mann Strecker, of Reading, Penn., in his " Rhap. et Hetero." No. 6, page 

 48, gives the geographical distribution of asterias as follows: — "The 

 *' ordinary form, with but little variation, occurs from Canada to Florida," 

 taking a southern range, while it extends west as far as Colorado. He 

 considers asterioides to be the tropical form of asterias, that brevieauda 



Note. — "Themsectsof separate arctic regions have a great mutual resem- 

 "blance, and the difference between them increases in the successive concentric 

 ■** circles from the above regions towards the equator. It has been said that the 

 ■"advance of the glacial period , was accompanied by tlie migration of insects 

 "southwards, and that the present distribution of insects was effected by the pre- 

 ■*' valence of this epoch, and by the succeeding temperate epoch." — F. Wnlbr, F. L, 

 S., in Can. Fnt., vol. Hi, 2^. I48. 



