INSECTS. 349 



whirl round each other with the greatest rapidity, and 

 appear to be incited by the greatest ferocity." 



The Agercnia fei onia 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 Eio 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.* 



Some moths also produce sounds; for instance, the males 

 of Thecophora fovea. On two occasions Mr. F. Buchanan 

 White f 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. 



Giard has always observed that the musky odor, which 

 is emitted by two species of Sphinx moths, is peculiar to 

 the males; J and in the higher classes we shall meet with 

 many instances of the males alone being odoriferous. 



Every one must have admired the extreme beauty of 

 many butterflies and of some moths; and it may be asked, 

 are their colors and diversified patterns the result of the 

 direct action of the physical conditions to which these 

 insects have been exposed, without any benefit being thus 

 derived? Or have successive variations been accumulated 

 and determined as a protection, or for some unknown pur- 

 pose, or that one sex may be attractive to the other? And, 



*Seeiny "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 Theco- 

 phora, see "Zoological Record," 1869, p. 401. For Mr. Buchanan 

 White's observations, " The Scottish Naturalist," July, 1872, p. 214. 



f " The Scottish Naturalist," July, 1872, p. 213. 



j " Zoological Record," 1869, p. 347. 



