in number; but three South African species perhaps offer an exception.
Mr. Wallace (78. Transactions, Linnean Society, vol. xxv. p. 37.)
states that the females of Ornithoptera croesus, 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, 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 (79. Proceedings,
Entomological Society, Feb. 17, 1868.), 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 useless at the beginning of the
season, and the females at the end, from the want of mates. (80. Quoted
by Dr. Wallace in Proceedings, Entomological Society, 3rd series,
vol. v. 1867, p. 487.) 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 very 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 more
numerous. Several entomologists concur in this view. Mr. Doubleday,
however, and some others, take an opposite view, and are convinced that
they have reared from the eggs and caterpillars a larger proportion of
males than of females.
Besides the more active habits of the males, their earlier emergence
from the cocoon, and in some cases their frequenting more open
stations, other causes may be assigned for an apparent or real
difference in the proportional numbers of the sexes of Lepidoptera,
when captured in the imago state, and when reared from the egg or
caterpillar state. I hear from Professor Canestrini, that it is
believed by many breeders in Italy, that the female caterpillar of the
279