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  • Bloodworm.png
Stack digit 9.pngStack digit 9.pngStack digit 9.pngStack digit 9.png
TypeBaitBoss summon
Bait Power4444%
Use time14 Fast
TooltipSummons The Old Duke if used as bait in the Sulphurous Sea
Enrages outside the Sulphurous Sea
RarityRarity Level: 13
Buy / Sell 2 Platinum Coin.png / No value
Research3 required
Dropped by
The Destroyer (On the Get fixed boi seed)1100%

The Bloodworm is a post-Moon Lord critter found in the Sulphurous Sea. They can be caught with any type of Bug Net.

Bloodworms act identically to Truffle Worms, slowly crawling along the floor and burrowing away from the player when they get too close to it. Also like Truffle Worms, Bloodworms cannot be used in normal fishing; instead, they are used to summon The Old Duke while fishing in the Sulphurous Sea.

Bloodworms can also be purchased from the Sea King for 2 Platinum Coin after The Old Duke has been defeated.


  • Bloodworms can be detected by the Lifeform Analyzer.
  • Bloodworms only spawn close to the bottom of the Sulphurous Sea, requring the player to dive deep underwater to find and catch them. Due to the depth they spawn, it's also possible for them to spawn near the top of the Abyss.
  • Bloodworms will not spawn if the Acid Rain event is currently ongoing.
  • Bloodworms will always be consumed upon summoning The Old Duke, regardless of any items the player has that reduce bait consumption.
  • Bloodworms can be found as soon as the Moon Lord is defeated, despite the fact that The Old Duke is supposed to be fought after defeating Polterghast.
  • The spawn rate of Bloodworms is halved after The Old Duke has been encountered once during the Acid Rain event.
  • The spawn rate is increased the lower the amount of other Bloodworms alive in the world:
    • If there are no Bloodworms, spawn rate is boosted by 400%.
    • If there is one Bloodworm, spawn rate is boosted by 256%.
    • If there are two Bloodworms, spawn rate is boosted by 144%.
    • If there are three Bloodworms, spawn rate is boosted by 64%.
    • If there are four Bloodworms, spawn rate is boosted by 16%.
    • Spawn rate will not be boosted if five or more bloodworms are alive.


  • The BestiaryBestiary entry for the Bloodworm: "Bloodworms are an exceedingly rare creature to stumble upon, as they burrow at the first sign of danger. It takes both exceedingly great patience, wisdom, and agility to catch one, leaving the worms ever having but a single natural predator."
  • The bait power's usage of the number 4 is a reference to superstition held in some Asian countries, such as China and Japan, about the mentioned number, due to it being a homonym for "death".
  • Similarly to the Truffle Worm, the Fisherman's Pocket Guide (and its combined accessories) will display a player's fishing power simply as "Warning!", due to the fact that The Old Duke will spawn when using this as bait in the Sulphurous Sea biome and no fish will be caught when not in the Sulphurous Sea biome.
  • In real-world bodies of water, the presence of bloodworms is an indicator of pollution, therefore it makes sense for this kind of creature to be present in the Sulphurous Sea, which is highly acidic and polluted.
  • Previously, the item's bait power was 69420%, as 69 and 420 are both numbers which are used in memes.


These history sections are still a work-in-progress, and may not yet contain changes relevant to the current version of the Calamity Mod.
  • Increased stack size from 20 to 9999.
  • Tooltip now clarifies that using it as bait summons Old Duke.
  • Spawn rates are now increased relative to the number of Bloodworms already existing. This occurs up until 4 are currently spawned, once 5 or more are spawned the increased spawn rates are removed. The maximum spawn rate boost is 5x and the minimum spawn rate boost is 2x.
  • Now has an increased spawn rate after encountering The Old Duke for the first time.
  • Now shows up on the Lifeform Analyzer and its upgrades.