Hay

I bought a new bale of hay yesterday from a different source than usual. I put some in a megazorb bag for a mate of mine and left it in the lounge. I had to go up north due to an emergency with Mum and have come back home and have loads of tiny little flies flying around :shock:

Obviously I can't categorically state that it's come from the hay but that's the only thing different in my absence (I drove up this morning and returned tonight so nothing else has been introduced)

Could they be in the hay? What are they? Are they dangerous to buns and should I throw the whole bale away?

It's pants that my usual source of organic hay stopped selling it