deathwatch beetle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several wood-boring beetles of the family Anobiidae that make a clicking sound with the head from inside furniture and other wooden structures. The sound has traditionally been regarded as a portent of death.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various beetles of the family Anobiidae that bore into wood and make a tapping sound.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun bores through wood making a ticking sound popularly thought to presage death