310 THE PRINCIPLES OF Part II. 



Walsh, who informed me of this statement, says that with P. 

 turnus this is certainly the case. Jn South Africa, Mr. R. Trimen 

 found the males in excess in 19 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 species, 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 butterfly. I may here add, that in Hyperythra, a genus of 

 moths, Guene'e 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 Societ}^ 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 

 Bombyx Yamamai, are lost at the beginning of the season, and 

 the females at the end, from the want of mates. 62 I cannot how- 

 ever persuade myself that these causes suffice to explain the great 

 excess of males in the cases, above ' given, of butterflies which are 

 extremely common in their native countries. Mr. Stainton, who 

 has paid such close attention during many years to the smaller 

 moths, informs me that when he collected them in the imago state, 

 he thought that the males were ten times as numerous as the 

 females, but that since he has reared them on a large scale from the 

 caterpillar state, he is convinced that the females are the most 



58 Four of these cases are given by Mr. Trimen in his ' Pdiopalocera 

 Africse Australis.' 



50 Quoted by Trimen, ' Transact. Ent. Soc' vol. v. part iv. 1866, p. 330. 



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



61 ' Proc. Entomolog. Soc' Feb. 17th, 1868. 



6 " Quoted by Dr. Wallace in ' Proc. Ent. Soc' 3rd series, vol. v. 1867, 

 p. 487. 



