WEEVILS— COCKCHAFERS. 67 



appeared musical." In this genus the sound is produced 

 by rubbing the tip of the abdomen, so rapidly that the 

 movements were scarcely visible to the eye, against the 

 under surface of the ends of the elytra, or wing-cases. 

 The tip of the abdomen, though roughened, is not con- 

 spicuously so, the ends of the elytra are shagreened, 

 tliough very finely, and WoUaston expresses his surprise 

 that so small an instrument could produce so loud a 

 noise. He describes a similar structure in other species 

 of the group. 



The cockchafers (Melolontha), besides the humming 

 of the wings, produce a sound which may almost be 

 called a voice. In the large trachea, immediately 

 behind each spiracle, is a chitinous process, or tongue, 

 which is thrown into vibration by the air during respi- 

 ration, and thus produces a humming noise. 



In the beetles, then, the sounds produced may be 

 divided into three classes : 



1. Incidental, such as those produced during 

 flight. 



2. Defensive. 



3. For signals, as in Longicorn beetles, Ateuches, 

 Anobium, etc. 



Laudois gives the following summary of the different 

 modes in which sounds are produced by the Cole- 

 optera : — 



1. Tapping sounds (Bostrychidse, Anobium). 



2. Grating sounds (Elaterida). 



3. Friction without rasping organs {Euchirus lon- 

 gimanus). 



4. Easping sounds produced by friction, viz. — 



(1) Pronotum on Mesonotum (Cerambycida, with 

 the exception of Spondylis and Prionus). 



