you'd hafta have a picture for anyone to suggest what they might be - there's dozens of small decomposer insects that can show up in/around a worm bin, but with peat normally being pretty sterile, I can't imagine it would have introduced anything - I'd think if they die outside the bin, they depend on the moisture

and you can use peat, but it's pretty useless for a worm bin, shredded paper is much better bedding and provides real food for the worms

Bill