Not to be confused with the Mulligan monster
A blue fly, with a blue heart above it.
Regardless of how many Flies are spawned, no more than five will follow Isaac into the next room.
It is not possible to spawn two Flies per hit while Guppy.
- Inner Eye and Mutant Spider - Can spawn multiple Flies with one attack.
- Technology 2 - Has a much higher chance of spawning Flies, due to Technology 2's high fire rate.
- This item's name and effect was based on the enemy of the same name.