PROPORTION OP THIS SEXES. 283 



In regard to butterflies in a state of nature, several observers have 

 been much struck by the apparently enormous preponderance of the 

 males.* Thus Mr. Bates. \ in speaking of several species, 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 100 to 1. In North America, Edwards, who 

 had great experience, estimates in the genus Papilio the males to the 

 females as 4 to 1; and Mr. Walsh, who informed me of this 

 statement, says that with P. turtius this is certainly the case. In 

 S. Africa, Mr. R. Trimen found the males in excess in nineteen spe- 

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

 the number of males as 50 to 1 female. With another species, 

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

 only five females during seven years. In the Island of Bourbon, M. 

 Maillard states that the males of one species of Papilio are twenty 

 times as numerous as the females. 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 the males in number; but three 

 South African species perhaps offer an exception. Mr. W r allace| 

 states that the females of Ornithoptera crasus, in the Malay Archi- 

 pelago, 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, Guenee 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, ![ 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 Labits 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 tbat, as M. 

 Personnat remarks, the males of the domesticated Bombyx Tamamai 

 are useless at the beginning of the season, and the females at the 

 end, from the want of mates.** I cannot, however, persuade myself 

 that these causes suffice to explain the great excess of males in the 

 above cases of certain butterflies which are extremely common in 

 their native countries. Mr. Stainton, who has paid vecj^lose atten- 

 tion 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 more numerous. Several entomologists concur 



*Leuckart quotes Meinecke (Waffner, " Hartdworterbuch derPhys.,"B. 

 Iv. 1858, s. 775), that the males of butterflies are three or four times as numer- 

 ous as the females. 



t " The Naturalist on the Amazons." vol. ii, 1863, pp, 228. 347. 



t " Four of these cases are given by Mr. Trimen iu his " Rhopalocera AfricaB 

 Australis." 



Quoted by Triraen, li Transact. Ent. Soc.," vol. v, part iv, 1866, p. 380. 



I " Transact. Linn. Soc.," vol. xxv, p. 37. 



1 " Proc. Entomolog. Soc.," Feb. 17, 1868. 



**Quoted by Dr. Wallace ia " Proc. Ent. Soc.," 3d series, voL T, 1867, p. 487. 



