Peat moss is a quite common medium that I use in growing Gesneriad plants but one annoying issue is there comes the 'Mushroom Flies' that fly around the terrarium. It's hard to catch or beat them due to they fly elusively. The simple solution is to grow some Pinguicula, commonly known as the butterwort ... it's a qualified "Predator" with no harm to human and catches flies with efficiency. Sometimes it also gives you a cute flower as reward.
I grow 3 butterwort hybrids which easily tolerate my environment because I am not collecting them, I just raise them as the Predator of Mushroom Flies.