Small black bugs in the medium

[plantlady]

I've been scratching my head trying to figure out what these little buggers are. They are black in color, and very small, much smaller than all the common pests.

I started noticing them in some phragmepediums that I have growing in semi-hydro culture. When I water the medium I occasionally see them exiting through the drainage holes and into my humidity trays.

Sometimes they appear to float on the water and they can even jump. Other times I've seen them actively moving around the insides of the pot.

My solution was to place my orchids in a well ventilated are and drench them with Ortho Systemic Insect Killer. It did not harm my plants and I have not seen the buggers return yet.

My fear is that they are root aphids, however all pictures online of root aphids do not resemble these insects in size. And the best guess that I have is that they are flea beatles, however I have not been able to accurately identify what they are and am curious to see if anyone else has this problem or perhaps knows what these curious little insects are.