6 SOUTH-AFRICAN BUTTERFLIES. 



Tlie gregarious and onTvard-flying habits of the Pierinm are well 

 known, and reach their climax in the genus Callidryas (see infra, 

 p. 185, and vol. i. p. 31), whose species have exceptional powers of 

 flight, well indicated by their large, solid thorax and thick, strongly- 

 veined wings. 



Mimicry is strikingly exhibited in this Sub-Family, and it was mainly 

 the study of the deceptively exact imitation of various South-Ameri- 

 can Danaince by species of the Pierine genus Lcptalis that enabled Mr. 

 Bates to give to science the satisfactory explanation of the phenome- 

 non to which I have adverted in vol. i. pp. 35—36. The $ s of Perrhyhris, 

 a genus very closely allied to Fieris, and a species of Eiderjje, also 

 mimic various Danaince; and one of the latter genus (^E. Tereas) closely 

 imitates the $ Papilio Zacynthus. Mr. Wallace, in the paper above 

 cited, commented on the imitation by the ^ s of various Malayan species 

 of Eronia of the common kinds of Danais in the same region, and 

 further brought to notice that mimicry occurred within the limits of 

 the Pierince themselves, specifying several cases in which the slow-flying 

 and showy species of Thyca are simulated by species of the genera 

 Prioneris and Picris. 



I am able to adduce two similar cases in South Africa, where the 

 slow-flying Mylothris Agathina is nearly copied by both sexes of Picris 

 Thy 8a and by the female of Eronia Argia ; while in Western Africa 

 Mylothris Poppca (Cram.) is the model followed by Pieris Rhodope (Fab.). 



The genus which is by far the best developed in South Africa is 

 Teracolus, white or yellow butterflies with a patch of bright colour — 

 orange, red, crimson, or violet — at the tip of the fore- wings. I have 

 discussed at length {infra, p. 82) the various groups of this large and 

 most difficult genus, which contains some of the most beautiful of all 

 the Pierince. 



Seasonal dimorphism — or palpable difference between the earlier 

 and later broods of the same species — has been shown to occur in the 

 well-known cases of Pieris Napi (Linn.), of which P. Bryonice (Ochs.) 

 is the early or " winter " form, and Anthocharis Ausonia (Hlibn.), of 

 which A. Bella (Cram.) is the " winter " brood. The progress of 

 observation of the life-history of butterflies has of late years gone to 

 show that instances of this kind of dimoriDhism are not, as was sup- 

 posed, limited to countries where a severe winter prevails, but occur 

 (and are probably more numerous) in tropical and sub-tropical regions 

 where the climate is divided into wet and dry seasons.-^ Three cases 

 in South Africa certainly exist, viz., those of Picris Charina, Boisd., 

 P. Thysa, Hopff., and P. Sevcri7ia (Cram.), in each of which the winter 

 or dry-season brood on the South-East coast is considerably smaller, 

 and in the two latter with enlarged black markings. Probable cases 

 are that Pieris alha (Wallengr.) is the dry-season brood of P. Pigca, 



^ See Mr. L. de Nic^ville's paper on Calcutta Satyrincv in the Journal of the Asiatic 

 Society of Bengal, vol. Iv. p. 239 (1886). 



