68 



AFRICAN MIMETIC BUTTERFLIES 



of A. egina, the female of that species is somewhat variable, and in some cases there is 

 much more red in the hind-wings than in the example figured. Nevertheless when placed 

 side by side the male Psetidacraea approaches much more nearly to the corresponding sex 

 of the Acraea than does the female. A perusal of the instances of mimicry given in these pages 

 will show that in very many cases the females only of mimicking species exhibit that tendency 

 to variation which results in the development of a mimetic pattern, whilst in other cases 

 both sexes are mimetic, but in aU cases the female mimicry is at least as good as, and often 

 much better than, that of the male. Only careful observation of the habits of P. hoisduvali will 

 furnish an explanation of its exceptional case. The mimicry is rather better on the under- 

 side. Probably the female, as usual in many species, is more retiring in its habits and 

 frequents wooded regions in company with the female model, in which case a rough approxi- 

 mation to the pattern of the latter may be a sufficiently effective protection. We have, 

 however, additional proof of the mimetic tendencies of this Pseudacraea in the fact that 

 in the east and south it becomes modified to the variety trimeni, and here it accompanies 

 the variety acara of Acraea zetes. Here the mimicry is still more perfect. Just as the form 

 acara frequently has a white suffusion in the discal area of the hind-wings, so P. hoisduvali 

 trimeni develops a similar white suffusion. The white hind- winged example of A. zetes 

 acara shown on Plate VI was drawn from a single example in my own collection, but since 

 I have had the opportunity of examining a large series of this butterfly I find that the 

 specimen is unusually small, the average size more nearly approximating to that of the 

 female shown at Fig. 6. In Trans. Ent. Soc, 1908, p. 552, Trimen described a form 

 from Rabai near Mombasa which is distinctly intermediate between trimeni and hoisduvali, 

 the deep ochreous apical patch in the fore- wing being reduced to a mere streak. The original 

 form hoisduvali extends along the west coast from Sierra Leone to Ogowe, whilst trimeni 

 is found from Natal to Mombasa and inland to Taveta. 



With reference to the habits of trimeni there is an interesting note by Mr. Marshall 

 quoted by Professor Poulton in Trans. Ent. Soc, 1902, p. 504, which is as follows : ' I feel 

 quite satisfied that Pseudacraea trimeni is a mimetic and not a protected species. In spite 

 of its larger size it looks wonderfully like A craea acara on the wing, and the first few examples 

 I caught completely took me in. Their flight is like that of all Pseudacraeas and Eur alias — 

 slow and sailing — so long as they are not disturbed ; but if struck at and missed they are 

 off like a shot, and do not often give one a second chance. At this particular spot (Malvern) 

 they are a good deal commoner than A. acara, which is only a rare visitor. The latter is, 

 however, common on the immediate coast, where P. trimeni is, I am told, pretty plentiful 

 in good seasons.' The Rev. K. St. A. Rogers has also given us some interesting particulars 

 in connexion with this butterfly in Trans. Ent. Soc, 1908. He there describes P. trimeni 

 as common at Rabai, often indeed commoner than the Acraeine models. It is found in the 

 same situations as the A craeas, though the flight is described as being more lofty and sustained, 

 and the insect is liable to fly rapidly when alarmed. It is evident that this author is inclined 

 to regard the mimicry as Miillerian, as he points out that ' the integuments of the thorax 

 are very tough and quite different from those of species which adopt a protective (cryptic) 

 appearance ' } 



^ It may he well at this point to call attention to case the difficulty of the great disparity in size be- 

 the resemblance of the underside of the great Papilio tween antimachus and even the largest of the red and 

 anlimachus, Dm., to that of Pseudacraea hoisduvali. black-spotted /I craeas. It is probable, however, that 

 The upperside of the former butterfly also has the further acquaintance with the habits and localities 

 appearance of a gigantic Acraea. We have in this of the species will show that the resemblance is not 



