The unlit bug lantern is a piece of Slayer equipment required to combat harpie bug swarms; without a lit bug lantern all attacks against them will be ineffective. The lantern is equipped in the off-hand slot, thereby disabling the use of two-handed weapons. Despite being a "lantern", this item cannot be used as a light source.
A Slayer level of 33 is required to wield the lantern, and must be lit using a tinderbox in order to be effective. A Firemaking level of 33 is required in order to light the lantern. Players assigned harpie bug swarms must possess the correct level in order to slay them, as Firemaking assistance will not allow the player to light the bug lantern. Players will still be assigned Harpie Bug Swarms even if they do not have 33 Firemaking.