488 NOISES OF INSECTS. 



largest, while those on each side became gradually smaller and lower ; and 

 it is, he is persuaded, in consequence of the air being forcibly driven out 

 of the trachea and touching these laminae that they are made to vibrate and 

 sound precisely in the same way with the glottis of the larynx. Dr. Bur- 

 meister (who remarks that Chabrier in his Essai sur le Vol des Insectes, 

 p. 45, &c., has also explained the hum of insects as produced by the air 

 streaming from the thorax during flight, and also speaks of laminae which 

 lie at the aperture of the spiracle), in order to be certain that the laminae 

 in question in the posterior spiracles of the thorax are alone concerned in 

 producing sound, also inspected the anterior ones, but without finding in 

 them any trace of these laminae. He explains the weaker and sharper 

 tones produced when the wings all but the very roots are cut off as resulting 

 from the weaker vibrations of the contracting muscles, and consequent less 

 forcible expulsion of the air when the vibratory organs are removed ; and 

 he thinks with Chabrier that some air may escape through the open trachea 

 of the wings which are cut off. Though he regards these laminae as the 

 cause of humming in bees and flies, he does not decide that other causes 

 may not produce the buzz of cockchafers, &c., in the thoracic spiracles of 

 which he could not discern them. 1 



Aristophanes, in his Clouds, deriding Socrates, introduces Chaerephon as 

 asking that philosopher whether gnats made their buzz with their mouth or 

 their tail. 2 Upon which Mouffet very gravely observes, that the sound of 

 one of these insects approaching is much more acute than that of one re- 

 tiring ; from whence he very sapiently concludes, that not the tail but the 

 mouth must be their organ of sound. 3 * 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 particu- 

 larly the capricorn-beetles the mandibles of whose larvae resemble a pair 

 of mill-stones 4 most probably do not feed in silence. A little wood- 

 louse (Atropos pulsatoria) which on that account has been confounded 

 with the death-watch is said also, when so engaged, to emit a ticking 

 noise. Certain two-winged flies seen in spring, distinguished by a very 

 long proboscis (Bombylius), 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 



Burmeister, Manual of Ent. 468 470. 9 Act. i. Sc. 2. 



* Mouffet, 81. 4 Linn. Trans, v. 225. t. xii. f 7 U 



