I have read Peace Lilly can attract bugs that kills them, we had a lovely one that died put this down to bugs/flies.
can't help with what to kill them with.
They all attract fungus gnats. The little buggers will come annoy you all day long. As soon as they feel they have been detected, they will fly towards something black and disappear. They also fly towards the human eye. You will lose focus and they make a get away.
I cling film the soil and hold the film down with pebbles-substitute (aggregate for use in concrete) so that they can't access the soil or come out of it. The stem of the plant has to be sealed as well. This fixes the infestation. The plants are watered from the bottom at the dish and are unaffected by the sealed soil. Can't tell you how to seal a complex stem system.