Chapter 11

IN this great Order the most interesting points for us are the differences in colour between the sexes of the same species, and between the distinct species of the same genus. Nearly the whole of the following chapter will be devoted to this subject; but I will first make a few remarks on one or two other points. Several males may often be seen pursuing and crowding round the same female. Their courtship appears to be a prolonged affair, for I have frequently watched one or more males pirouetting round a female until I was tired, without seeing the end of the courtship. Mr. A. G. Butler also informs me that he has several times watched a male courting a female for a full quarter of an hour; but she pertinaciously refused him, and at last settled on the ground and closed her wings, so as to escape from his addresses. Although butterflies are weak and fragile creatures, they are pugnacious, and an emperor butterfly* has been captured with the tips of its wings broken from a conflict with another male. Mr. Collingwood, in speaking of the frequent battles between the butterflies of Borneo, says, "They whirl round each other with the greatest rapidity, and appear to be incited by the greatest ferocity."

* Apatura iris: The Entomologist's Weekly Intelligence, 1859, p. 139. For the Bornean butterflies, see C. Collingwood, Rambles of a Naturalist, 1868, p. 183.

The Ageronia feronia makes a noise like that produced by a toothed wheel passing under a spring catch, and which can be heard at the distance of several yards: I noticed this sound at Rio de Janeiro, only when two of these butterflies were chasing each other in an irregular course, so that it is probably made during the courtship of the sexes.*

* See my Journal of Researches, 1845, p. 33. Mr. Doubleday has detected (Proc. Ent. Soc., March 3, 1845, p. 123) a peculiar membranous sac at the base of the front wings, which is probably connected with the production of the sound. For the case of Thecophora, see Zoological Record, 1869, p. 401. For Mr. Buchanan White's observations, the Scottish Naturalist, July, 1872, p. 214.

Some moths also produce sounds; for instance, the males Theocophora fovea. On two occasions Mr. F. Buchanan White* heard a sharp quick noise made by the male of Hylophila prasinana, and which he believes to be produced, as in Cicada, by an elastic membrane, furnished with a muscle. He quotes, also, Guenee, that Setina produces a sound like the ticking of a watch, apparently by the aid of "two large tympaniform vesicles, situated in the pectoral region"; and these "are much more developed in the male than in the female." Hence the sound-producing organs in the Lepidoptera appear to stand in some relation with the sexual functions. I have not alluded to the well-known noise made by the death's head sphinx, for it is generally heard soon after the moth has emerged from its cocoon.

* The Scottish Naturalist, July, 1872, p. 213.