I’m afraid they could be spider mites … 
This was my first thought as well. I actually shuddered at the first pic and became horrified as I scrolled down and I’m dealing with aphids. Spider mites scare me! 
Dang thats a bummer!.. what soil did you buy? Fox farm by chance? At least they aren’t russets.
1 gallon water
1/4 cup Dr bronners baby soap unscented
1/2 cup 70% isopropyl
Kill Jill kill those spideys
Are you still in veg?
No webs as of yet.
Still in veg. On one plant only. Definitely the mites…
Yepp. Mixing up the kill shit right now.
Short story: you can cull that plant and spray the others, if you want to also save that plant you may lose the battle, there are many right now … 
That’s pretty severe case, @george said it best. Cull that one and treat the rest. They are throughout the greenhouse.
Johnny’s one and done would work well now and through flowering.
And by cull I mean handle gently and burn
Lowes
Neam oil ready mixed spay
Kills spider mites excellent.
Broad mites
Forget about it, but they are even smaller than
Spider mites, that’s what makes the so evil
You dont notice till it’s a done deal.
But ya the pre mixed neam oil will clear that up
If you mix yourself be very careful.
It works for a host of issues.
You must bath them under leaves
Soil really well but it works I promise.
