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
281