Could someone please help me with this, my Horsefields enclosure is crawling with hundreds of little flies . where are they coming from and why are they in there? Any advice much appreciated
They or eggs may have been in the substrate when you bought it.
What are you using and did you bake it or soak it with boiling water when you first used?
Prob best to remove it and replace.
The little flies are detrivores. The breed and feed on the substrate/food waste/poop in the enclosure.
They'll appear of their own accord. It's nothing to do with eggs in the substrate.
They are harmless to both you and your torts and an inevitability of having a warm, damp environment.
Spot clean the enclosure on a daily basis. Some people introduce a few pill bugs as biological control. Catch them outside - look under rotting wood or stones