Phals have black, pinpoint-size pests

[Newby phal grower]

There were some flies around my phals, which I got rid of using flypaper.
I also read about placing potato slices on top of the medium overnight. Now there are no flies, but every morning I see black, pinpoint-size crawling things on the potato slices. What are these, and is there a better way to get rid of them than potato slices? Many thanks.

[camille1585]

They're probably just little critters that feed on decaying material in the pots, so harmless to the plants. When was the last time you repotted? They could be a sign that your Phals need new medium