308 



NOISES OF INSECTS. 



the tail but the mouth must be their organ of sound. 1 But 

 after all, the friction of the base of the wings against the 

 thorax seems to be the sole cause of the alarming buzz of the 

 gnat as well as that of other Diptera. The warmer the 

 weather, the greater is their thirst for blood, the more 

 forcible their flight, the motion of their wings more rapid, 

 and the sound produced by that motion more intense. In 

 the night — but perhaps this may arise from the universal 

 stillness that then reigns — their hum appears louder than 

 in the day: whence its tones may seem to be modified by 

 the will of the animal. 



Sounds, also, are sometimes emitted by insects when they 

 are feeding or otherwise employed. The action of the jaws of 

 a large number of cock-chafers produces a noise resembling 

 the sawing of timber ; that of the locusts has been compared 

 to the crackling of a flame of fire driven by the wind ; indeed 

 the collision at the same instant of myriads of millions of 

 their powerful jaws must be attended by a considerable 

 sound. The timber-borers also — the Buprestes ; the stag- 

 horn beetles ; and particularly the capricorn-beetles — the 

 mandibles of whose larvae resemble a pair of mill-stones 2 — 

 most probably do not feed in silence. A little wood-louse 

 (Atropos pulsatoria) — which on that account has been con- 

 founded with the death-watch — is said also, when so en- 

 gaged, to emit a ticking noise. Certain two-winged flies 

 seen in spring, distinguished by a very long proboscis (Bom- 

 bylius), hum all the time that they suck the honey from the 

 flowers ; as do also many hawk-moths, particularly that 

 called from this circumstance the humming-bird {Macroglossa 

 stellatarum), which, while it hovers over them, unfolding its 

 long tongue, pilfers their sweets without interrupting its 

 song. The giant cock-roach (Blatta gigantea), which abounds 

 in old timber houses in the warmer parts of the world, makes 

 a noise when the family are asleep like a pretty smart rapping 

 with the knuckles — three or four sometimes appearing to 

 answer each other. On this account in the West Indies it is 

 called the Drummer ; and they sometimes beat such a re- 



• Mouffet, 81. 



2 Linn. Trans, v. 225. t. xii. f. 7. b. 



