A creature within the swarm’s space must succeed on a DC 10 Constitution saving throw or take 10 (4d4) poison damage, or 5 (2d4) poison damage if the swarm has half its hit points or fewer, and be poisoned for 1 minute. On a successful save, the target takes half as much poison damage and is not poisoned. A poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on a success. If the target’s saving throw is successful or the effect ends for it, the target is immune to the swarm’s poisonous cloud for the next 24 hours.