NOISES OF INSECTS. 383 
tion of the base of the wings against the thorax seems to 
be the sole cause of the alarming buz of the enat 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—theu 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 cockchafers 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 bee- 
tles (Zucani); and particularly the capricorn-beetles 
(Cerambycide)—the mandibles of whose larvee resemble 
a pair of mill-stones?—most probably do not feed in 
silence. A little wood-louse (Psocus pulsatorius, Latr.) 
—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, L.), 
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 (Sphinz 
4 Linn. Trans, v. 255. t, xi. fi 7. db. 
