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 lamine 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 laminge which 
lie at the aperture of the spiracle), in order to be certain that the lamin 
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 lamina. 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 lamin 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.? 
Aristophanes, in his Clouds, deriding Socrates, introduces Cheerephon as 
asking that philosopher whether gnats made their buzz with their mouth or 
their tail? 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. 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 collitidn 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 larva: resemble a pair 
of mill-stonest— 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 (Maeroglossa stellatarum), which, 
while it hovers over them, unfolding its long tongue, pilfers their sweets 
1 Burmeister, Manual of Ent, 468—470. 2 Act. i. Se. 2, 
3 Mouffet, 81, # Linn, Trans. v. 225. t. xii f 7 be 
