188G.] 219 



Although small insect-eating birds ai'c wonderfully numerous at Callao, the larvae 

 are untouched by them, and I have never bred an Ichneumon-fly or any other parasite 

 from the numerous larvse I have reared. In the United States, however, Mr. Riley 

 informs us that the larva is attacked by a Dipterous fly, Masicera (Tachina) 

 archippivora, Riley. The tenacity of life in the imago is very remarkable, as is also 

 its longevity, as according to Mr. S. II. Scudder, it has been kept alive for fifteen 

 months. 



The original home of Anosia Plexippus is the American continent, 

 where it enjoys a very wide range, extending from the Hudson's Bay 

 teoritory and Canada to the Amazon region and Bolivia, or (if we 

 regard Erippus, Cram., as a geographical race merely) to the estuary 

 of the Rio de la Plata. Mr. J. Jenner Weir has received it from 

 Moose Fort (lat. 50. 20 JN".) where snow lies on the ground for eight 

 months of the year, and I heard of it, though I did not see it, at 

 jEsquimalt, Vancouver Island, in nearly the same latitude. It thus 

 ranges over nearly 90° of latitude, and extends farther North than any 

 other of the DanaidcB (D. Tytia in Japan, and D. Chrysippus in 

 South-eastern Europe, barely, if at all, reaching the 40th parallel). 

 Nearly everywhere throughout this vast region, it appears to be 

 I common, and in many places, especially in the United States, it is one 

 of the most abundant butterflies. Here it is often observed in 

 prodigious swarms, and according to Mr. Eiley (to whose lucid and 

 admirable account of the insect, in the Third Annual Eeport on the 

 Insects of Missouri, I am very much indebted) the air is sometimes 

 filled with the butterflies to a height of 300 to 400 feet. These vast 

 swarms usually appear in the autumn, and some of them at least, 

 Mr. Eiley states, migrate southwards to warmer regions at the 

 approach of winter. 



Of late years this range, great as it is, has extended in a 

 wonderfully steady and rapid manner across the whole breadth of the 

 Pacific Ocean, and far into the Malay Archipelago. Anosia Plexippus, 

 unobserved by the early voyagers to the Sandwich Islands, is now 

 abundant and firmly established there. In the Marquesas Islands, 

 where it is now the commonest butterfly, I was informed by a Eoman 

 Catholic missionary, who had resided forty years on the island of 

 O. Hiva-Oa (Dominica), that he distinctly remembered seeing the 

 first specimens about the year 1S60 : certainly so conspicuous an 

 addition to the very limited insect-fauna of these islands could not 

 have been long overlooked. In the Society Islands (Tahiti and Eimeo) 

 and the Cook and Hervey groups (Mangaia, Earotonga, Aitutaki, and 

 Atiu) I saw both the butterfly and its food-plant Asclepias curassavica 

 in plenty, and the latter, indeed, is a pest to cultivation in some of the 



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