All you need to do is:

Hide in water

Swing a touch

Or get your self a frog to follow you round

One more thing on Xbox you need to be in 3rd person so you can damage them.

If being targeted get into the water and they won't attack even if ur only ankle deep.

These things are the worse things in the game. It seems as if you kill one swarm, 2 more show up in its place.🤦‍♂️

Use a torch to kill them

A helpful tip should use a few more words

Go into third person (hold down the “map” button on Xbox) and hit them with a torch. WARNING- if there are to a lot of swarms, you’ll need to repair your torch because they will break really fast.