Section IV., 1884. [ 233 ] Teans. Roy. Soc. Canada. 



XII. — Notes on the Occurrence of Certain Butterflies in Canada. 

 By W. Saunders, Loudon, Ontario. 



(Eead May 21, 1884.) 



Important changes have evidently taken place in the recent past affecting the geo- 

 graphical distribntion of some of the butterflies now reg-arded as Canadian, and similar 

 changes are also occurring at the present time. It is well known that some butterflies 

 occur in considerable abundance every year in many localities, while others, usually rare, 

 occasionally become plentiful. Some are restricted within certain limited areas, others, 

 though extremely rare, are found at widely distant points, while others again, once rare 

 and formerly found only in the most southern portions of our country, are now much 

 more common and have been taken in some of the more northern sections of Ontario and 

 Quebec. Seeing that these gradual change:S in the location of species are occurring, it is 

 important that all who are interested in this department of biological study should record 

 any observations they may have the opportunity of making, so as to aid in preparing the 

 way for a fuller knowledge of the geographical distribution of our species, and of the 

 causes which affect such distribution. 



Papilio cresphontes, formerly known as P. Tkoas, is a notable instance of a butterfly once 

 extremely rare in our Province, and found only in its most southern county, having with- 

 in fifteen or twenty years disseminated itself throughout the gTeater part of Ontario. I 

 well remember the great interest with which collectors looked upon the first Canadian 

 specimens of this butterfly. They were taken more than twenty years ago in the neigh- 

 bourhood of Amherstburgh and were regarded as great rarities. This insect was first 

 described by Cramer, and was figured by Boisduval and LeConte in their work on the 

 Butterflies of North America, published in 1833, where it is referred to as a common 

 insect in the Southern States, feeding in the larval condition on the orange and lemon 

 trees. It is still abundant in the South, and is regarded as a noxious insect on account of 

 the injury it does to the foliage of trees of the Citrus family ; the larva is known there 

 under the common name of " the orange dog." 



The species composing the Rue family, Rutacece, to which the genus Citrus belongs, 

 all have their leaves dotted with pellucid glands containing pungent or bitter aromatic 

 volatile oils. The genera are very unlike each other. We have in this country, besides 

 the orange and lemon, the northern and southern prickly ash, Xanthoxylum Americanum 

 and Carolinianum ; the hop-tree or wafer-ash, Plelea trifoliatu ; and two introduced plants, 

 the garden Rue, Ruta graveolens, and Dictamnus frazinella, the latter being cultivated in 

 gardens as an ornamental herbaceous plant. Wandering from its home among the orange 

 groves, this butterfly is enabled to recognise the allied genera in this family as suitable 



Sec. IV., 1884. 30. 



