I haven't encountered one directly, only heard of them, but these cocoons match the description. And based on their size...

[ Yeah, the moths would also have to be rather large. Given that Thancred has also heard that they give off a dust that causes people to see things that are not truly there, he sees no reason to stay near them. There's plenty of other places to forage.

Daisy picks up on the fact that there must be a reason he knows all this, and Thancred quickly nods. ]

Aye, once before. It was some time ago now. I never thought we would return, let alone like this...