Reddit reviews Catchmaster 904 Clear Window Fly Trap - 1 pack of 4 traps

They are probably fungus gnats. The gnats themselves are harmless but the larvae eat soil, and if there's too many, roots. Large infestations can damage plants by the larvae destroying roots. Buy sticky fly paper and put it right around the plant (like within 6 inches, above, the more hte better). It will capture all the adults so they can't lay more eggs. I use this stuff and just stick it vertical at the edge of the pot like this.

I also put the paper on all the windows in my room and it is stunning how many fungus gnats there are, I didn't even realize. I have a ton of plants growing in my room but didn't notice the gnats until I put up the fly paper (was originally after house flies).

I think the gnats like moist conditions, you should water the plant way less. Let it get bone-dry between waterings. I think a fast-draining cactus soil would help defeat the gnats as well.

We had an infestation in our house recently (turned out it was under the trash can in the garage) and we had a bunch of flies about a week after we found the white guys. Might wanna check under the sink, and hose out the trash cans, if you find any more. Also you could get sticky paper and put it in the top corners of your windows to see what you catch. Could be house flies, could be gnats.

Excellent idea to let it callus and start over. My friend overwaters everything, I can't convince him to let the top of the soil dry out. Good luck!