What is "deathtick"

Deathwatch \Death"watch`\ (?; 224), n.

1. (Zo["o]l.)

   1. A small beetle ( Anobium tessellatum and other allied species). By forcibly striking its head against woodwork it makes a ticking sound, which is a call of the sexes to each other, but has been imagined by superstitious people to presage death.

   2. A small wingless insect, of the family Psocid[ae], which makes a similar but fainter sound; -- called also deathtick.

      She is always seeing apparitions and hearing deathwatches.
      --Addison.

      I did not hear the dog howl, mother, or the deathwatch beat.
      --Tennyson.

2. The guard set over a criminal before his execution.