350 



SCIENCE FROM AN EASY CHAIR 



with occasionally a little heap of yellow dust on the 

 ground beneath them. This last sign is in fact the only 

 proof you can have that the holes are not ancient and the 

 burrows deserted, and that the enemy is still alive and at 

 work. Rarely, if ever, can you see either the grub or the 

 completed beetle into which it changes after forming a 

 cocoon within the burrows, for they very seldom leave 

 their excavations. But if you 

 break up the wood you will 

 find a surprising number of 

 long, cylindrical passages, run- 

 ning side by side, and for many 

 inches, through the deeper part 

 of the wood, so that it may 

 be quite rotten and ready to 

 crumble, although presenting 

 an uninjured surface save for 

 the little round holes here and 

 there. In these passages you 

 will find both the grubs and 

 the adult beetles. 



A closely-allied and some- 

 what smaller species oi Anobium 

 common in houses is of a more 

 voracious character, not con- 

 fining itself to dry wood, but 

 eating bread, biscuits, rhubarb, 

 ginger, and even cayenne pepper. This second kind, 

 called Anobium paniceum, is the real "book-worm"; it 

 gets into old libraries, and the grubs bore their cylindrical 

 tunnels from cover to cover of the undisturbed volumes 

 In a public library twenty-seven folio volumes standing 

 side by side were perforated in a straight line by one 

 individual Anobium, grub or book-worm, and so regular 

 was the tunnel thus eaten out that a string could be passed 



FIG. 62. a, the death-watch 

 beetle (Xestobium tesscllatum) 

 of the natural size (one-third of 

 an inch long) ; b, the same 

 beetle enlarged ; c, the beetle 

 (Anobium domesticum) whose 

 grub is the furniture-worm, of 

 the natural size, a side view. 



