Chap. VIII.] SEXUAL SELECTION. 301 



no less than about a hundred in number, which inhabit the 

 Upper Amazons, says that the males are much more numerous 

 than the females, even in the proportion of a hundred to one. 

 In North America, Edwards, who had great experience, esti- 

 mates in the genus Papilio the males to the females as four to 

 one ; and Mr. Walsh, who informed me of this statement, says 

 that with P. turnus this is certainly the case. In South Africa, 

 Mr. E. Trimen found the males in excess in nineteen species ; 58 

 and in one of these, which swarms in open places, he estimated 

 the number of males as fifty to one female. With another spe- 

 cies, in which the males are numerous in certain localities, he 

 collected during seven years only five females. In the island of 

 Bourbon, M. Maillard states that the males of one species of 

 Papilio are twenty times as numerous as the females. 59 Mr. 

 Trimen informs me that as far as he has himself seen, or heard 

 from others, it is rare for the females of any butterfly to exceed 

 in number the males ; but this is perhaps the case with three 

 South African species. Mr. Wallace 60 states that the females of 

 Ornithoptera crcesus, in the Malay archipelago, are more common 

 and more easily caught than the males ; but this is a rare butter- 

 fly. I may here add, that in Hyperythra, a genus of moths, 

 Guen6e says, that from four to five females are sent in collections 

 from India for one male. 



When this subject of the proportional numbers of the sexes 

 of insects was brought before the Entomological Society, 61 it was 

 generally admitted that the males of most Lepidoptera, in the 

 adult or imago state, are caught in greater numbers than the 

 females ; but this fact was attributed by various observers to the 

 more retiring habits of the females, and to the males emerging 

 earlier from the cocoon. This latter circumstance is well known 

 to occur with most Lepidoptera, as well as with other insects. 

 So that, as M. Personnat remarks, the males of the domesticated 

 Bomhyx yama-mai are lost at the beginning of the season, and 



58 Four of these cases are given by Mr. Trimen in his c Rhopalocera 

 Africfe Australis.' 



63 Quoted by Trimen, ' Transact. Ent. Soc.' vol. v. part iv. 18G6, p. 

 830. 



60 • Transact. Linn. Soc.' vol. xxv. p. 37. 



e "Proc. Entomolog. Soc.' Feb. 17, 1868. 



