236 SEXUAL DIMORPHISM 



and is most pugnacious, perching on the tops of bushes, and 

 darting forward to attack any other butterfly that may fly 

 past. Trimen states that this species is a bold and active 

 insect, frequenting flowers in gardens and open spots, and 

 that the habit of settling on the ground is more practised by 

 the male. Danais chrysippus, the imitated form, appears to 

 frequent open plains, the -larva feeding on Asclepiad plants, 

 which are of no great size. Marshall 1 says that in India the 

 species is common everywhere, but the dry hot plains of 

 Northern India seem to suit it, and there it is almost the only 

 butterfly which flourishes in the dust and glare. There is 

 thus a general similarity of habits between the female IT. 

 misippus and D. chrysippus, but there is little at present to 

 show that the male of the former species has habits which 

 correspond to the difference of his coloration from that of the 

 female. It must be remembered, however, that the habits and 

 conditions have not been carefully observed and described, 

 because collectors and specialists have not yet realised their 

 importance. 



The general distribution of the varieties suggests that 

 climate has something to do with the variations. Thus the 

 form B. alcippus is characteristic of the humid forest region 

 of West Africa. 



The adherents of the theory of mimicry maintain that in 

 the West Indies and South America H. misippus is an intro- 

 duced species, because the pattern form D. chrysippus does 

 not occur in America. But the facts offer two obstacles to 

 their views, which they do not discuss. The first is How is 

 it that one species has been introduced without the other, 

 considering that in Asia and Africa the two species occur 

 together? The second difficulty is How is it that the 

 species which owes its existence in the Old World to the 

 protection afforded by mimicry, flourishes when introduced 



1 Butterflies of India, Burmah, and Ceylon. 



