Bites

_Melee Weapon Attack:_ +5 to hit, reach 0 ft., one creature in the swarm's space. _Hit:_ 18 (4d8) piercing damage, or 9 (2d8) piercing damage if the swarm has half of its HP or fewer, and the target must succeed on a DC 13 DEX save or have its flesh shredded by the attack. A creature with shredded flesh loses 4 (1d8) HP at the start of each of its turns as the wound bleeds profusely. Any creature can take an action to stanch the wound with a successful DC 10 WIS (Medicine) check. The wound also closes if the target receives magical healing.