Tiny bug ID

I have bugs in the open pots in my propagation box which I would like ID'd.  They are very tiny (I need a 15x magnifier to see them) and have fat non-shiny black bodies similar in shape to a beetle.  Would anyone know what they are and whether they pose a threat?  I'll attempt a photo but doubt the camera will register anything.

I considered just using Confidor but concerned it may prove more harmful to the seedlings than the bugs (I ruined the growing tip of a young pachypodium lamerei seedling this way).

I have had pretty good results with confidor on my seedlings. Especially against mealy bug. I would give it a try on a few plants and see how it goes before treating the whole lot.

I've noticed various little critters in my open seedling trays and have not had any adverse effects.
Probably nothing to be too concerned about if they're not attacking your plants, in terms of treatment if they are causing trouble I would probably lean towards something a little more natural and less harsh.
Haven't needed to thus far but maybe a mild mix of water, dish detergent and chilli powder should do the trick that's what I use on my other plants unsure if this would be ok for cacti seedlings though.

Sneaky, I can't be sure it was the confidor that ruined the pachypodium seedling - the tip was already showing issues which is when I applied the insecticide.  I occasionally find a mealy in the propagation box but it's pretty rare.

Walker, I haven't noticed any problems from the bugs - indeed they've been hard to find at the moment.  Your spray sounds interesting - I'll keep it in mind.

Your bugs sound like aphids. They will cause damage when in large numbers but aren't a big problem.

HN, I googled some images - and yes I believe you're right.  Mine were truly tiny so I assume they were babies.  Haven't noticed them for a while so hopefully they won't grow into a problem.