Jar of Flies

Unlimited   Shop Treasure Room Shop   (page 4, column 9, line 4)

Jar of Flies is an activated item added in Afterbirth.

Effects

• 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

  Flight. Converts small enemy flies into blue flies.

  set. Collecting three items from this set will transform Isaac into a giant humanoid fly.

Notes

• Kills by blue flies and locusts (including flies from the jar) and shooting familiars (including 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 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 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.

Interactions

• Car BatteryCauses Isaac's activated item to activate twice on each use.: No effect.

Synergies

• Hive MindIncreases the size of blue spiders and Blue Flies and doubles the amount of damage they deal.: Flies are bigger and deal double damage.
• Fish TailItems and trinkets that generate blue flies or blue spiders will generate twice as many.: Doubles the number of flies that spawn.
• SchoolbagAllows Isaac to hold two active items.: Flies will be gained even while the Jar of Flies is in the inactive slot.

Trivia

• The item's pickup quote references the tagline of the Pokémon games.
• With Booster Pack #2, this item's sprite fills up with more flies depending on how many flies it contains. This is based off of this Steam Workshop mod by Stewartisme.
• The item is likely a reference to the Alice In Chains album of the same name.

Seeds

 PC  KTHW HTAY (First floor, in the shop)

Fly Items

• ???'s Only FriendSummons a big attack fly that can be controlled with the shooting direction-keys.
• Angry FlySpawns a fly familiar that orbits around a random enemy and deals 5 damage per tick to enemies it comes in contact with.
• BBFSpawns a familiar that flies around the room in a manner similar to the Boom Fly and explodes on contact with an enemy. Respawns after ten seconds.
• Best BudWhen hit, summons a white attack fly similar to Distant Admiration for the current room.
• Big FanSpawns a large orbital familiar that blocks enemy projectiles and deals slight contact damage to enemies.
• Distant AdmirationA red attack fly circles further out than the Halo of Flies / Pretty Flies, but closer than Forever Alone. Deals more damage than Forever Alone.
• Forever AloneSpawns a blue attack fly that orbits a long distance from Isaac.
• Friend ZoneA white orbiting fly which deals 3 contact damage per tick to enemies. This familiar orbits Isaac at a middle length distance somewhere between Distant Admiration and Forever Alone.
• Halo of FliesSpawns two pretty fly familiars that block enemy shots and deal contact damage to enemies.
• Hive MindIncreases the size of blue spiders and Blue Flies and doubles the amount of damage they deal.
• Infestation1-3 Blue flies randomly spawn every time Isaac gets hit.
• Jar of FliesEvery time Isaac kills an enemy, a fly will be added to the jar, up to a maximum of 20. Using the Jar of Flies will release all the flies that are currently in the jar as friendly blue flies that will damage enemies.
• Lost FlyA familiar fly that moves in a straight line and attaches itself to the first obstacle or wall it comes into contact with in each room. If any enemies walk into its path, it will deal 7 contact damage per tick. If the obstacle it is attached to is destroyed then it will continue rolling in the direction it was previously travelling until it meets another wall or obstacle.
• The MulliganTears have a 1/6 chance of spawning allied blue flies when they hit an enemy.
• Obsessed FanA purple fly familiar that follows Isaac's movements on a 3 second delay and deals contact damage to enemies.
• Papa FlyA blue fly familiar follows Isaac's movements on a 3 second delay. Papa Fly will fire tears at nearby enemies.
• SkatoleAll types of fly except Boom Fly and Red Boom Fly become passive and slowly move towards Isaac. Does not prevent contact damage.
• Smart FlyAfter Isaac takes damage, this fly will deal continuous touch damage to whatever enemy caused the damage until it is dead. The fly will then systematically attack 1 enemy at a time until the room is cleared.