I think I have heard them be called carrion flies. They are similar to the size of my gliders out melo's but skinny and a little longer. Problem is there infested my cultures and teaching the others how to fly and I'm losing alot of cultures. I have not fed with them. My hydie cultures are ok. For now. These little flies can squeeze into the cultures through the mesh vent. Any ideas what to do? I have never seen these before.