Swarm Wild Shape

Swarm movement. The swarm can occupy another creature's space and vice versa and does not require any rolls for moving through the space of a hostile creature (though opportunity attacks still apply. The swarm can move through any opening large enough for a Tiny insect. 

One too many. The swarm can't regain hit points or gain temporary hit points. The swarm cannot interact with objects.

Bite. Melee Weapon Attack: + Dex Modifier + Proficiency Modifier to hit, reach 0 ft., one target in the swarm's space. Hit: 4d4 + Dex Mod piercing damage.

Disperse. Bonus action: Dodge, giving enemies disadvantage on attack rolls until the start of the swarm's next turn.

Engulf. Movement: When a creature ends it's turn within 5ft of the swarm, the swarm can move into the space of this creature.