Biter

Biters are little worms that help the player defeat enemies. they can either be summoned by the Swarm or by the weapon affix "Biters Crawl From The Dead"

Biters can attack multiple enemies at once, and are usually a one-hit kill by enemies. enemies will target biters if they are closer to it then the player. If Biters are not killed by an enemy, they explode after a short period of time.

Biters also appear to have little bows on their head, hence the icon of the swarm.