These large alien insects are slightly venomous flies that lay their eggs in the corpses of those buried in the muck near Atlantean ruins.

Armor Class 15
Hit Points 30
Speed 5 ft., fly 40 ft.

Damage Resistances: bludgeoning, piercing, and slashing
Damage Immunities: poison, psychic
Condition Immunities charmed, frightened, paralyzed, petrified, poisoned, prone, restrained, stunned
Senses darkvision 60 ft., passive Perception 10

Swarm: A swarm of murder flies takes double damage from area effect attacks. The swarm can occupy one or more other creatures' spaces and vice versa, and the swarm can move through an opening large enough for a Tiny monster.