68 VARIETY OF OEGANS OF SOUND AMONG BEETLES. 



(2) Prosterniim on Mesosternum (OmalopKa 



Irimnea). 



(3) Elytra with rasp at tlie end (Curculionida ; 



Dytiscida, Pelobius). 



(4) Coxa3 with rasp (Geotrupes, Ceratophyus). 



(5) Cover-margin rasp rubbing against the thigh 



{Ghiasognathus Grantii). 



(6) Pygidiiim with two rasps in the middle 



(Crioceris, Lema, Copris, Oryctes, Necro- 

 l)horus, Tenebriouida). 



(7) Abdomen with a grating-ridge and four 



grating-plates (Trox sahulosus). 



(8) Abdomen with two toothed ridges rubbing 



on cover-margin rasp (Elaphrus, Blethisa, 

 Cychrus). 



(9) Elytra rubbing with under-wing rasp {Pelohius 



Merrmanni). 



(10) Wings rubbing against abdominal ringlets 

 (Melohntha fullo). 



5. Exploding sounds from the tail (Brachinus). 



6. Sounds produced by the spiracles (Melolontha). 

 Graber, moreover, has shown by a number of 



interesting experiments * that the power of hearing is 



by no means confined to those beetles which are known 



to produce sounds themselves. 



Passing on to other groups of insects, flies and gnats, 



besides the humming of the wings, produce sounds, 



like the cockchafer, through the spiracles, some of 



which are especially arranged for this purpose. If a 



fly be caught and held between the fingers, it will 



generally make a loud and peculiar sound. The hum. 



of the mosquito is only too familiar to most of us. 



* " Die Choidotoual Siunesoi-gaue der Insekteii," Areli. fiir Mic. 

 Anal, 1882. 



