Bebeliths are a type of fantastic insect that can be encountered in dNetHack. Their biggest threat to the adventurer is their armor-damaging shred attack. Each successful hit attempts to disenchant a single piece of worn armor. If a piece of armor has been disenchanted to the point that its net contribution to AC is 0, the next shred attack that hits the item will destroy it. Artifacts are immune to destruction by bebelith shred attacks, but not disenchantment.
Bebeliths follow the same movement rules as grid bugs: they cannot move diagonally. Players can therefore use positioning to kill them without taking a hit.
‘Long we live and long we weave
Till we have filled this space.
Then, as before, we will leave
To hunt another place.
Our task ends when the weak are gone.
then fill new spaces with our spawn!'