260 THE CANADIAN NATURALIST. [Aug. 



mentioned in these lists is P. oleracea, a species wticli may be 

 distinguished at a glance from P. rajxe, the markings being 

 altogether different. Mr. Couper captured a specimen of P. 

 rajyce within the city limits of Quebec, about five years ago, but 

 did not investigate the subject, though considering the insect a 

 rare one, his special study being coleoptera. This is the earliest 

 notice of the butterfly in Canada; and it evidently points out 

 Quebec as the locality of introduction, and fixes the period at 

 about seven or eight years ago. 



With respect to the means by which it has been brought into 

 the country, some plausible conjectures may be advanced. Of 

 course the introduction took place during the season of navigation. 

 The turnip, cabbage, and other kindred vegetables, constitute the 

 principal food plants of the insect; and, adhering to one of these 

 it must have been carried across the ocean, either in the ess:, 

 larva, or chrysalis, — the last being the most unlikely, as the larva 

 always forsakes its food-plant, and becomes a pupa in some shel- 

 tered situation, usually under the coping of a wall, &c. The eggs 

 are laid on the under side of cabbage and turnip leaves, where the 

 larva, on emerging, find themselves in close proximity to their 

 food. Perhaps the vegetable refuse thrown from one of our ocean 

 steamers on her arrival, has contained a few eggs or larvas, which 

 under these unfavourable circumstances, have retained their vita- 

 lity ; and from these have sprung the imagines destined to become 

 the parents of the species in Canada. 



The habitat of the insect is still very limited. After making 

 enquiry, I do not think that it has extended more than forty miles 

 from Quebec as a centre^ so that a circle of eighty miles diameter 

 would include the present habitat. This may seem great progress 

 during the short period of its naturalization, but, considering the 

 fecundity and habits of the species, it is not surprising. 



There is some importance connected with the introduction of 

 this butterfly, apart from the scientific interest of the subject to 

 entomologists. Hitherto, Lower Canada has possessed but one 

 species of the genus Pieris (P. oleracea, Harris ; Pontia casta ^ 

 Kirby,) and this species so insignificant in numbers, at least in , 

 the Quebec region, that its depredations have passed unnoticed. 

 The new importation, however, must be regarded in a different 

 light. As the insect is now permanently settled in the country, 

 is very prolific, and the larvas extremely voracious, we may anti- 

 cipate its becoming a great pest to farmers and gardeners, not only 

 where it is now found, but ultimately in the whole of Canada, and 



