84- INSECTS. 



The use of the dilatable bladder-like organs on the 

 sides is not ascertained, but it seems to be generally 

 considered as a means of defence. 



These little creatures are eminently predaceous, and 

 of two confined together, only one is likely to be 

 found afterwards if they be left undisturbed for a little 

 while. 



There are several small wood-boring beetles which 

 belong to this division. They are generally dull in 

 colour, hard, and somewhat cylindrical in form, and the 

 antennae vary, being of a thread-like and tapering form, 

 or more or less deeply toothed, or, as in the Anobium 

 (PL III., fig. 2) (the beetle of which the common " Death 

 Watch" is the larva), approaching to the pectinated club 

 of the Stag-beetle, but without the -knee-like joint. The 

 larvae feed upon every variety of dry vegetable matter, 

 and the round tunnels of the beetle book-worm are but 

 too familiar a sight to his human representative. In 

 the case of books, the devastations of these insects may 

 be prevented by the frequent opening and exposure of 

 the volumes; but it is extremely difficult to stop the 

 progress of the wood-boring species when they have once 

 established themselves within the woodwork of houses, 

 furniture, &c. ; and this, too, is not even hindered by 

 the interposition of substances which seem impossible 

 to digest ; for, even as the human book-worm finds his 

 way through the heaviest authors, so have these been 

 known to work their way through leaden bullets and 

 the leaden lining of cisterns. 



So considerable is the mischief effected by these 

 beetles, that in the choice of woods for shipping, 

 the preference of kinds least subject to their attacks 

 becomes a matter of importance. 



