HEARING IN INSECTS. 



93 



B (I 



A Father loiiir-leirs (Pedida rivnsa) ; a a, the poisers, B, The poisers, 

 a a, separate, C, the poisei's, a a, and the winglets, b b. From De Geer. 



often repeated with the same result ; but when he 

 mutilated or removed either one or both wing-lets, the 

 buzzing; ceased*. 



De Geer, upon examination of one of the wasp-flies 

 (SyrphidfB), satisfied himself that the buzzing- was 

 produced by the friction of the root or base of the 

 wings against the sides of the hollow in which they 

 are inserted. For this purpose, he took hold of each 

 wing with his fingers and thumb, and stretchin:^ 

 them out in opposite directions, to prevent their mo- 

 tion, and at the same time taking care not to hurt 

 the insect, no sound was produced. Not con- 

 tented with this, he cut off both wings of a syrphus 

 very near their roots ; but this did not prevent it from 

 buzzing any more than the excision of both the poisers 

 and the winglets, for, on examining- the parts with a 

 microscope, he perceived that the remaining roots of 

 the wings continued to vibrate, and the buzzing to 

 go on, nor did it cease till he completely eradicated 

 the wings t. 



* Wiedemann, Archiv., ii. 210 — 17. f Memoires, vi., 13. 



