172 progeedings of the academy of [jan_ 



6. The Female of Neophasia terlooti, another North American: 



Mimic of Danaida plexippus. 



Dr. Skinner remarks (34, p. 27): "What is the cause of the ex- 

 traordinary antigeny seen in Neophasia terlooti? The male in this 

 species is white and the female orange. The female of the species 

 was once sent to me as a ' little Danais' and it really looks like one.. 

 Here would be a good opportunity to build up a mimicry theory. " ^ 

 At the time when I read these words I had never seen the species, 

 but Dr. Skinner has now very kindly sent me a male and female 

 from Reef, Arizona (Nov. 2, 1903: Biederman). There can be no 

 doubt that the female is a mimic of D. plexippus. The comparison 

 between the yellow of the under surface exposed in the position of 

 rest and the orange of the upper surface, the blackening of the veins 

 on the upper surface of the hind wing and other details to be de- 

 scribed below are quite inexplicable on any other hypothesis. The 

 mimicry is rather rough and there is no approximation in the shape 

 of the wings. In both respects this female stands in about the same 

 position as the females of the Neotropical Perrhybris {"Mylothris'').. 

 I am greatly indebted to my friend for this opportunity of examining 

 and writing on what is to me an entirely new example of butterfly- 

 mimicry in North America — another result of its invasion by the 

 Old World genus Danaida. My friend Commander J. J. Walker, 

 who has had an intimate experience of the allied Neophasia menapia 

 in Vancouver Island, tells me that during flight the latter is one of the 

 feeblest of Pierines and that it suddenly appears upon the wing in 

 immense numbers. He has kindly permitted me to make use of the 

 following unpublished extracts from his journal, on H. M. S. "King- 

 fisher" at Esquimalt, Vancouver Island: 



1882, August 7: "Day still, hot, and cloudless. During the 

 forenoon I was agreeably surprised by the appearance of a good 

 number of specimens of a very pretty "White" butterfly. . . . 

 It seems to come very near to Leucophasia, by the elongate shape 

 and delicate texture of its wings, as well as by the rather short antennae 

 and hairy palpi. . . . They were flying sluggishly in the sunshine 

 over the water, and the signalman and I caught 15 on the poop in a 

 very short time [the ship being about 300 yards off shore]. . . . 

 Landed at 4 P. M.; the Leucophasia? was" still on the wing, and I 



•* 



iDr. F. A. Dixey remarked of N. terlooti in 1905 {Proceedings of the Entomo- 

 logical Society of London, p. xx) : "This latter butterfly is especially interesting, 

 as possessing a female which closely resembles some of the mimetic forms ot 

 Euterpe." 



