Swarm of Ravenous Insects

If the swarm starts its turn in the same space as a Large or smaller corpse, the corpse is destroyed, leaving behind only what it was wearing or carrying.

The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny creature. The swarm can't regain Hit Points or gain Temporary Hit Points.

Melee Attack Roll: +4, reach 5 ft. Hit: 20 (4d8 + 2) Piercing damage, or 11 (2d8 + 2) Piercing damage if the swarm is Bloodied, and the target has the Poisoned condition for 1 minute as insects burrow inside it. The condition ends early if a spell or effect restores Hit Points to the target. While Poisoned, the target takes 4 (1d8) Piercing damage at the start of each of its turns. A creature reduced to 0 Hit Points by this damage dies.