March, 1886.] 217 



ANOSIA PLEXIPPUS, L. {DANAIS ARCHIPPUS, F.) : A STUDY IN 

 aEOaKAPHICAL DISTRIBUTION. 



BY JAMES J. WALKER, R.N., F.E.S. 



At the present time, when Entomologists are discussing the 

 probability of the beautiful butterfly first described by Linne under 

 the name of PapiJio {Danais) FJexippus (but which is perhaps better 

 known by the Fabrician name of D. Archippus') becoming a permanent 

 resident in our islands, on the strength of the dozen specimens or 

 more captured last autumn in the South of England, it may be 

 interesting to give a brief account of the insect and its transformations, 

 and theUgto consider its present geographical distribution. It is in 

 the latter respect that the butterfly is most remarkable, for within the 

 last thirty or forty years it has spread from its original home in the 

 American continent over more than half the warmer regions of the 

 globe, and now bids fair to soon become as world-wide in its distribution 

 as our more familiar " Painted Lady," Pyrameis cardui. 



My acquaintance with Anosia Plexippus (or rather with the 

 well-marked Erippus, Cram., by many Entomologists raised to the 

 rank of a distinct species) began at Monte Video, where, in December, 

 1880, ] found the insect in small numbers. A few months later, at 

 Callao, I had abundant opportunities of observing it in all its stages, 

 it being one of the commonest butterflies of the locality. Here one 

 could make sure, on almost any day in the year, of seeing the imago 

 on the wing, though it was most abundant in January and February, 

 and scarcest in July. The handsome larva, too, was always to be 

 found wherever its food-plant grew, and as it was singularly easy and 

 interesting to rear, I was seldom without several feeding in my cabin 

 on board the " Kingfisher." During our cruise among the South Sea 

 Islands in 1883, the first visitor from the shore of any island we 

 touched at was usually the bold flying Danais, and in some of them, 

 considering the recent introduction of the butterfly, its abundance 

 was very remarkable. 



As most Entomologists are doubtless familiar with the perfect 

 insect, it need not here be described. According to my own experience, 

 it seems to prefer waste weedy places and gardens near towns and 

 villages, its flight being strong, though rather heavy, and it is not very 

 difiicult to catch. As if aware that it is a distasteful morsel to all 

 insect-eating creatures, it seeks no concealment whatever, and I have 

 often seen two or three, at sunset, roosting together on the summit of 

 some tall weed in the middle of a field, and visible a hundred or more 

 yards off. 



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