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PSYCHE. 



ORGAN OF THE CAMBRIDGE ENTOMOLOGICAL CLUB 



EDITED BY B. PICKMAN MANN. 

 Vol. I.] Cambridge, Mass., July, 1875. [No. 15. 



The Introduction of Danaida Plexippus into the 

 Pacific Islands. 



[In a letter from Dr. Luther H. Gulick; with additional comments.] 



" In 1852, I returned, after eleven years' absence, to the 

 Sandwich Islands, and. my brother John drew my attention to 

 the fact that the so-called American milk-weed (Asclepias) 

 had, during my absence, been introduced, and had spread so 

 rapidly as to be already ranked, in that tropic climate, with 

 troublesome weeds. My brother had, early after its introduc- 

 tion, noticed that in whatever part of the group the milk-weed 

 appeared, there also what he called the milk-weed butterfly 

 (Danaus) appeared ; a butterfly unknown on all the Sandwich 

 Islands till after the introduction of the milk-weed. 



" In 1857, a number of choice plants were sent me at Pon- 

 ape or Ascension Island of the Caroline Range, from Honolulu, 

 by our small missionary brig of about one hundred tons bur- 

 then, whose diminutive hold and cabin were several times ran- 

 sacked in every corner before it reached our island, so that no 

 such butterfly as the Danaus could easily have been concealed 

 there. The plants were in glass-covered cases, as closely sealed 

 from the air as it was possible to make them. The vessel sailed 

 from Honolulu on the 24th of June, and reached Ponape, two 

 thousand miles or more from the Sandwich Islands, on the 18th 

 of August, or after fifty-four days, several days after which the 

 case was for the first time opened, thus making a period of about 

 eight weeks from the time of its closure. ( )n the voyage to 

 Ponape, the vessel touched at Apaiang of the Gilbert Islands 

 and Ebon of the Marshall Islands, both low coral atolls, where 

 butterflies of any kind are all but unknown, and at Kusaie or 



