190 MR, G. F. HAMPSON ON STRIDULATION [Mar. 1, 



upper surface, and I suggest that the longitudinal fold acts as a 

 channel for the tarsus, the ridges on each side striking against the 

 spines. Mr. E. Meyrick informs me that this insect makes a loud 

 buzzing sound during flight, and the first time he heard it he thought 

 a " humble-bee" was buzzing round his hat ; he tells me that the 

 insect during flight swings rapidly up and down in the air, and he 

 thought the vibration of the air on the membrane might account for 

 the sound. 



The only other Lepidoptera known to make a similar clicking 



Fie. 2. 



<6. 



Hecatesiafenesirata, Boiad. cJ, 

 Fore wing. 



sound are some of the species of Ageronia, e. g. A. feronia, fornax, 

 amphinome, and arethusa, as was first discovered by Darwin during 

 the voyage of the * Beagle/ and confirmed by Wallace, and again by 

 Fritz Miiller, who says that he also observed it in Eunica margarita 

 and a small brown butterfly which he could not capture. 



Darwin says that when a pair of Ageronia feronia were chasing 

 each other they produced a clicking sound similar to that produced 

 by a toothed wheel passing under a spring catch, and that the noise 

 was produced at short intervals and was audible at twenty yards' 

 distance. Wallace says the noise was never produced by a single 

 specimen, but only when a pair were chasing each other, and he 

 imagined it was in some way produced by the contact of the two 

 insects ; but Bigg- Wither noted that the butterfly settled head down- 

 wards with its wings outspread, and that if approached it raised its 

 wings sharply once or twice, producing a whip-like sound, and that 

 it also made the same sound while on the wing. 



Ed. Doubleday examined the butterfly, and found a small mem- 

 branous sac between the costal and subcostal nervures of the fore 

 wing, with a structure along the subcostal nervure like an Archi- 

 medean screw; he very properly disclaimed this structure being 

 necessarily connected with the sound, and, as Scudder pointed out, 

 these are merely the swollen base of the subcostal nervure found in 

 so many NympTialince and the tracheal vessel in the nervure. 



Swinton says that the sound is produced by the costal nervure 

 of the hind wing, which is ridged like a file, being received into and 

 rubbing against a small depression of the fore wing ; but, as Scudder 



