Mr. Doubleday has called my attention to M. Staudinger's (82. 'Lepidopteren-Doubletten Liste,' Berlin, No. x. 1866.) list of Lepidoptera, which gives the prices of the males and females of 300 species or well- marked varieties of butterflies (Rhopalocera). The prices for both sexes of the very common species are of course the same; but in 114 of the rarer species they differ; the males being in all cases, excepting one, the cheaper. On an average of the prices of the 113 species, the price of the male to that of the female is as 100 to 149; and this apparently indicates that inversely the males exceed the females in the same proportion. About 2000 species or varieties of moths (Heterocera) are catalogued, those with wingless females being here excluded on account of the difference in habits between the two sexes: of these 2000 species, 141 differ in price according to sex, the males of 130 being cheaper, and those of only 11 being dearer than the females.
The average price of the males of the 130 species, to that of the females, is as 100 to 143. With respect to the butterflies in this priced list, Mr. Doubleday thinks (and no man in England has had more experience), that there is nothing in the habits of the species which can account for the difference in the prices of the two sexes, and that it can be accounted for only by an excess in the number of the males. But I am bound to add that Dr. Staudinger informs me, that he is himself of a different opinion. He thinks that the less active habits of the females and the earlier emergence of the males will account for his collectors securing a larger number of males than of females, and consequently for the lower prices of the former. With respect to specimens reared from the caterpillar-state, Dr. Staudinger believes, as previously stated, that a greater number of females than of males die whilst confined to the cocoons.
He adds that with certain species one sex seems to preponderate over the other during certain years. Of direct observations on the sexes of Lepidoptera, reared either from eggs or caterpillars, I have received only the few following cases: (See following table.) So that in these eight lots of cocoons and eggs, males were produced in excess. Taken together the proportion of males is as 122.7 to 100 females. But the numbers are hardly large enough to be trustworthy. On the whole, from these various sources of evidence, all pointing in the same direction, I infer that with most species of Lepidoptera, the mature males generally exceed the females in number, whatever the proportions may be at their first emergence from the egg.
| Males | Females | |
| The Rev. J. Hellins* of Exeter reared, during 1868, imagos of 73 species, which consisted of | 153 | 137 |
| Mr. Albert Jones of Eltham reared, during 1868, imagos of 9 species, which consisted of | 159 | 126 |
| During 1869 he reared imagos from 4 species consisting of | 114 | 112 |
| Mr. Buckler of Emsworth, Hants, during 1869, reared imagos from 74 species, consisting of | 180 | 169 |
| Dr. Wallace of Colchester reared from one brood of Bombyx cynthia | 52 | 48 |
| Dr. Wallace raised, from cocoons of Bombyx Pernyi sent from China, during 1869 | 224 | 123 |
| Dr. Wallace raised, during 1868 and 1869, from two lots of cocoons of Bombyx yamamai | 52 | 46 |
| Total | 934 | 761 |
(*83. This naturalist has been so kind as to send me some results from former years, in which the females seemed to preponderate; but so many of the figures were estimates, that I found it impossible to tabulate them.)