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appears in our catalogues. At the same time, though isolated from the 

 eastern States by arid plains of great extent and mountain heights of 

 arctic cold and severity, our insects, including those from Europe, have 

 nearly all found their way into the fields, orchards and vineyards of the 

 Pacific States. 



Among other interesting traits exhibited by these immigrant insects is 

 their capacity for adapting themselves to climatic and other conditions so 

 varied and so different from those to which they were indigenous. In 

 many cases such adaptation is accompanied by noteworthy modifications 

 of habit, and even, in a few species, of structure. 



The latest invader from Europe which has appeared in our immediate 

 locality is the Cabbage or Rape butterfly {Piert's rapes, Schrank). More 

 than ten years ago, in an article on the various " Cabbage-worms," Prof. 

 Riley called attention to this insect, which had then appeared only in the 

 vicinity of a few northern seaports, and predicted its spread westward and 

 southward ; with the further assurance that, once among us, it would prove 

 vastly more destructive and difiicult to eradicate than any of our native 

 pests of the same family. 



This prediction was abundantly fulfilled during the past summer (1879), 

 much sooner than had been anticipated. From July to October the "green 

 worms" were on every cruciferous garden vegetable — the second brood of 

 the season, evidently — being thus numerous and destructive. In the flower 

 garden also they made known their unwelcome presence. Here, singu- 

 larly enough, they rejected the stocks, the sweet Hyssum, and the Candy- 

 tuft, plants belonging to the botanical family which they most affect, in 

 favor of the Mignonette, which belongs to an entirely different family. It 

 is worthy of mention that this plant — the Mignonette — is likewise the only 

 plant outside of the Cruciferce upon which the larva of our most abundant 

 indigenous species {Pieris protodice) will feed. 



The perfect insect of P. rapes is a delicate white butterfly of medium 

 size, slow in flight and seldom rising high in the air. Both sexes bear a 

 superficial resemblance to the male of our native protodice, but may be 

 distinguished from it a glance by the more or less intense yellow color of 

 the under-surfaces of the wings and their more conspicuous black tips. 



There are probably three distinct broods of this insect in this latitude, 

 though the longevity and continued fecundity of the butterflies make it 

 very difficult to draw the line of demarkation between these broods. Larvic 

 of various sizes and in greater or less numbers may be found at any time 

 from spring until late in autumn. Hibernation takes place in the chrysa- 

 lis stiite. The unusually warm weather of the autumn of last year (1S79) 

 had the eflFect to bring out prematurely a large proportion of butterflies 

 from the last brood, with which I was experimenting. This unseasonable 

 emergence was likewise observed in the open air. These individuals did 

 not, of course, survive the winter, and the spring brood would be thereby 

 diminished. It is not unusaul for insects which hibernate in the pupa 

 state to occasionally send forth a stray individual in autumn ; but that so 



