13 



3, 1845, "a peculiar structure in tlie wiugs of this butterfly which seems 

 to be the means of its making its noise." He says: 



It is remarkable for liavina: a sort of drum at the base of the forewiusjs, between 

 the costal nervure and the subcostal. These two uervures, moreover, have a peculiar 

 screw-like diaphragm or vessel in the interior. 



Darwin also alludes to a statement in Langsdorff's travels (1803-'07) 

 that ''a butterfly called Fcbrua hoffmanseggi makes a noise when flying 

 away like a rattle." This name probably refers to Agcr.fercntina, which 

 was called Ager. februa by Hiibner. 



In addition to this genus, I have observed the power of stridulation 

 in two other butterflies, viz, in those of the genus Prepona, also natives of 

 Troi)ical America, and in Charaxes sempronius of Australia. The noise 

 of Prepona is only made as it takes wing from the trunks of the trees, 

 on which it is also fond of resting, and is not repeated during its flight) 

 It is therefore most probably in this case used as a defense against 

 birds or other enemies. The Charaxes as it alights upon a bunch of the 

 beautiful and sweet-scented flowers of Bursaria spinosa closes its wings 

 with a grating sound not unlike that of the Prepona, and repeats the same 

 as it is disturbed from its resting place. In butterflies it would appear that 

 the noises are all caused, as Mr. Swinton suggests, by the rubbing of 

 one vein of the upper wing against a corresponding vein in the lower 

 wing, and probably they are all produced by slight modifications of the 

 same structure, and it would appear that the power of stridulation is 

 confined to the Nymplialid group, in which, as will be readily seen, a 

 large development of the veins of the wing, particularly towards their 

 bases, occurs. 



There is very considerable difference in the sounds produced by the 

 moths, that of one species having been likened by the older authors to 

 " the voice of anguish, the moaning of a child, the signal of grief." This 

 description a])plies to the well-known European Sphinx {Acherontia) 

 atropos, familiarly known as the '' Death's Head Moth," which gives 

 out a very singular and plaintive cry, not unlike that (though in a 

 greater degree) produced by a captive beetle of the Geotrupid or Coprid 

 group when pressed between the finger and thumb. The noise of the 

 great atropos has caused it to be regarded with superstitious terror, and 

 this added to the grotesquely horrid mark of the skull and eye-sockets 

 upon the thorax has made it in the districts in which it abounds an 

 object of awe and terror. It is somewhat strange that, in this age of 

 entomological research, the means by which the sound is produced by 

 this species is yet unknown, comparative anatomists being considera- 

 bly at variance in their opinions on the subject. Some observers have 

 stated that the larva of this insect has also the power of emitting a sort 

 of squeaking noise. 



In our own country, if any one has ever noticed a large swarm of the 

 pretty little moth, so injurious to our grape-vines {Alypia octomaculata), 

 about a bush of flowers, he will have been conscious, if his ears were 



