Fly

Corpse Flies and Sewer Flies are a smaller, faster flying versions of Buzzcutters, which are only spawned by other enemies.

Behavior
Sewer Flies are spawned in groups of 3 or 5 by Hammers, while Purulent Zombies (Graveyard) spawn 6 Corpse Flies, which are connected by electric rays.

They attack as normal Buzzcutters, follow the player as usual, and inflict the same stun debuff, however, Corpse Flies will only attack once the Purulent Zombie that spawned them is killed.