72 MORE MINOR HORRORS 



have described is, we believe, the mechanism 

 by means of which the first vibrations are 

 produced. 



In the same periodical M. Jousset de 

 Bellesme ^ confirms the statement that both 

 Dipterous and Hymenopterous insects emit 

 two sounds — one deep and one acute, and 

 states that the latter is usually the octave 

 of the former. It is this double note which 

 gives rise to the peculiar buzzing associated 

 with these two orders of insects. M. de 

 Bellesme, like M. Perez, discards the view that 

 acute sounds are due to any action of the 

 issuing air in the stigmata, and attributes 

 it to the vibrations of the pieces of the thorax 

 which support the wing, and which are moved 

 by the muscles of flight. It is usually stated 

 that these muscles are not inserted into the 

 wing, but into the sides of the thorax, to 

 which the wing is so attached that when the 

 lateral walls of this part of the body are 

 deformed by the action of the muscles the 

 wings move up and down. But whether this 

 be the case or not, it is clear that the vibra- 

 tions of the sides of the thorax caused by the 

 muscles of flight — and causing the vibrations 

 of the wing — ^will synchronise in number with 

 these wing vibrations, and will give forth the 

 same note. The existence of the higher note 



1 Compt. Rend. Acad. Paris (1878), Ixxxvii, p. 535. 



