The Descent of Man

even in the proportion of a hundred to one. In
North America, Edwards, who had great experience,
estimates 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. R. Trimen found the males in
excess in 19 species (76. Four of these cases are
given by Mr. Trimen in his 'Rhopalocera Africae
Australis.'); 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 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. (77. Quoted by Trimen, 'Transactions
of the Ent. Society,' vol. v. part iv. 1866, p. 330.)
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