NYMPHALID^. 301 



it emerges. When seen in the snnsliine in the lieight of perfection, 

 the wings show pleasing iridescent tints varying from green to bine 

 and pnrple, or even red. This insect is rarely seen in the northern 

 pai't of our conntry before July, as it is supposed that neither the 

 perfect insect nor tlie egg or chrysalis is able to withstand the rigors 

 of our winter, and that the first specimens to be seen in our region 

 are migrants from the south. This is not strictly true, for on several 

 occasions both my brothers and I liave taken this butterfly early in 

 May in New England, proving that occasionally the insect succeeds 

 in weathering our severe winter either in the chrysalis or mature 

 state. 



At times during September or October immense numbers of these 

 butterflies are seen in scattered flocks apparently migrating either in 

 search of food or toward a warmer region. I have never been so 

 fortunate as to witness one of these flights, but from a gentleman 

 residing in northern Illinois, who saw such a migration in 1894, I 

 obtained the following facts : The butterflies were very abundant 

 near Chicago in that year, and toward the last of September tliey 

 formed immense flocks and might be seen every afternoon streaming 

 in a southeasterly direction. One evening tliousands collected on a 

 dead tree near this gentleman's house, completely covering its twigs 

 and branches. 



A good many other kinds of butterflies have been known to 

 assemble in flocks of countless thousands, and have even been 

 observed many miles at sea flying high in air. 



The geographical range of this Danais is very great, being now 

 distributed over a large portion of the earth's surface, although it 

 was originally a strictly American species. It is now common in the 

 Sandwich Islands, Samoa and most of the islands of the Malay 

 Archipelago, while it is plentifully distributed over Australia. These 

 distant lands have been colonized by it only within very recent 

 years. This butterfly with many others has been placed in a new 

 genus and given a new specific name within recent years, and now 

 by many collectors goes by the title of Anosia plexippus : and right 

 here I wish to write a few words in regard to the scientific names of 

 insects and the changes which are being made by almost every new 

 writer on the subject of entomology. This constant change of name 

 and the almost endless separating of the species into new genera is 

 one of the most senseless as well as the most needless obstacles 

 put in the way of those who desire to acquire a knowledge of ento- 



