Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki

Added in Afterbirth

Jar of Flies is an activated item added in The Binding of Isaac: Afterbirth.


  • Killing an enemy adds a fly to the jar, up to a maximum of 20.
  • Upon use, releases Blue Flies equal to the number of flies in the jar.
  • This item belongs to the Beelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.


  • Kills by blue flies and locusts (including flies from the jar) and shooting familiars (including 15►Incubus Incubus) do not add flies to the jar.
  • Blue spiders, orbital familiars, and chasing familiars do add flies to the jar.
  • Friendly enemies such as from the 15►Friendly Ball Friendly Ball add flies to the jar, but not those spawned from other enemies.
  • Batteries do not affect the number of flies in the jar.
  • Enemies must be actually killed to add a fly; transformations (such as Gapers turning into Pacers) or knockouts (such as incapacitating a Globin) do not count as kills.
  • Destroying a shopkeeper will count as a kill.
  • With items that kill normally unkillable enemies, killing things like Stone Grimaces will add flies to the jar.
  • Killing minions in the Hush fight does not add flies to the jar.


  • Added in Afterbirth †Fish Tail Fish Tail: Doubles the number of flies that spawn.
  • 15►Hive Mind Hive Mind: Flies are bigger and deal double damage.
  • Added in Afterbirth †15►Schoolbag Schoolbag: Flies will be gained even while the Jar of Flies is in the inactive slot.


  • 15►Car Battery Car Battery: No effect.
  • Added in Repentance15►Uranus Uranus: Enemies frozen by Uranus do not grant extra flies, even if shattered. Only enemies killed with bombs will add flies.
  • Added in Afterbirth †15►Void Void: Flies will not collect when absorbed by Void, making the interaction worthless.

In-game Footage[]


  • Removed in Repentance The item's pickup quote references the tagline of the Pokémon games. The quote said "Gotta catch 'em all?"
  • Added in Afterbirth † With Booster Pack #2, this item's sprite fills up with more flies depending on how many flies it contains. This is based on this Steam Workshop mod by Stewartisme.
  • The item is likely a reference to the Alice In Chains album of the same name.


PC KTHW HTAY (First floor, in the shop)


Bug Bug! The synergy of 15►The Ludovico Technique The Ludovico Technique with 15►Brimstone Brimstone or 15►Technology Technology will not spawn flies.

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