Yep, take the beetles out and change everything.
Were are you getting the soil and decor/branches?
You could try putting the soil and branches in a throw-away foil pan and pooring boiling water in it. Let it soak over night and then take the soil/branches out and let them dry. The temp. from the boiling water should kill the mold.
Also, try not to keep it overly moist/wet, and make sure there is enough air circulation.
Also, in the future is you see a tiny speck of mold growing just scoop it out and throw it away.