Bites

Melee Weapon Attack: +5 to hit, reach 0 ft., one creature in the swarm's space. Hit: 14 (4d6) piercing damage, or 7 (2d6) piercing damage if the swarm has half of its hp or fewer. The target must make a DC 13 Constitution saving throw. On a failure, a creature takes 10 (4d4) poison damage and is euphoric for 1 minute. On a success, a creature takes half the damage and isn't euphoric. A euphoric creature has disadvantage on saving throws. The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.