1176 THE BUTTERFLIES OF NEW ENGLAND. 



a plant foreign to its soil that he may have the fruit ready to his hand. 

 Without the natural hindrances which prevent its supremacy in its native 

 home, it thrives so vigorously, if otherwise adapted to the place, as to 

 8up[)lant the natural denizens of the soil : these are supporting numerous 

 animals, which in their turn suffer. 



So it has doubtless been in all ages of the world, where by any of the 

 multifarious means wliich nature employs she has herself upset the balance 

 she liad established, by bringing into a flora or a fauna some new element 

 from without. Indeed, the history of animal and plant life has been a 

 story of colonization. Any one who has observed the rapidity with which 

 weeds spread over new countries, has read of the rabbit nuisance in Aus- 

 tralia or seen the sparrow nuisance in America, w^ill comprehend what a 

 force colonization may have been. It was closely linked no doubt with 

 the introduction of new types in past ages of the world. 



The measurement of the spread of a newly introduced species has rarely 

 been attempted. Indeed, in the nature of things it could scarcely ever be 

 made except under circumstances which may fairly be deemed artificial, 

 that is, in countries tolerably well settled with people intelligent enough 

 to report accurately. Rarely, too, is the date of introduction known. 

 Yet as this could be approximately determined for the European cabbage 

 butterfly recently Imported into this country, and as by its ravages of a 

 common garden crop it would make itself known by the damage it did and 

 so force itself upon observation, it was believed that the correct measure 

 of its spread might have some import for future investigation, and perhaps 

 its lesson for him who would designedly introduce a new creature without 

 regard to its relations to other animals. 



The butterfly, Pieris rapae, was first noticed in Canada, and the actual 

 history of our knowledge of its first appearance there is as follows : — Mr. 

 William Couper, a taxidermist and general collector, addicted especially to 

 Lepidoptera and a good observer, living in Quebec, first captured a few 

 specimens in 1860 in the immediate vicinity of that city ; he then looked 

 upon the insect as a great rarity, and indigenous to Canada. 



In 1863 a new collector appeared in Quebec, Mr. G. J. Bowles, who, 

 capturing it and finding no such insect described in American works, ap- 

 plied to Mr. Couper, only to discover him equally at a loss. Mr. Bowles 

 then wrote to Mr. William Saunders of London, Ontario, and to myself, 

 and we both assured him that it was the European insect. In April and 

 July 1864, these gentlemen read papers before local societies, both of 

 which were published in whole or in part, and from these we learn that in 

 1863 the butterfly was very common and destructive in the neighborhood 

 of Quebec and at Laval fifteen miles north, and had extended thirty miles 

 to the northwest along the north shore of the St. Lawrence, though they 

 had not been noticed beyond Point Levis on the south, nor taken at St. 



