The Scarab Bow is a pre-Hardmode bow that is sometimes dropped by Scarabeus. It converts the arrows you shoot into Scarab Arrows. If a Scarab Arrow lands on a block rather than hitting an enemy, it converts into a Beetle that randomly picks a direction to crawl for a few seconds before despawning. If the Beetle hits a wall (even if it's a block high), it will stop moving, until it despawns. The Beetle will pierce through several enemies (as opposed to the arrow which does not pierce), and despawn after about 2 seconds. The Beetle cannot be harmed, as it is a projectile.
Its best modifier is Unreal.