NYMPHALIDiE. 
301 
it emerges. When seen in the sunshine in the height of perfection, 
the wings show pleasing iridescent tints varying from green to blue 
and purple, or even red. This insect is rarely seen in the northern 
part of our country before July, as it is supposed that neither the 
perfect insect nor the 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 have 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, 1 
obtained the following facts: The butterflies were very abundant 
near Chicago in that year, and toward the last of September they 
formed immense flocks and might be seen every afternoon streaming 
in a southeasterly direction. One evening thousands 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- 
