Yes, they're mites. But I'm uncertain if they are causing any problem.

The wilting of your plant might be eased if you cut off at least half the length of the leaves. It's wise to pre-moisten potting mix by getting it barely moist throughout before you pot up a plant. It's easy to moisten dry mix if you add a small amount of hot water, fluff up the mix and, then, repeat those 2 steps until evenly moist throughout.

We did pre-moisten the potting mix and it took several weeks for the plant to reach this point, so unfortunately that's not the problem. Also, since we repotted 9 walking iris at once and only the 2 with the mites are dying (and the others thriving), I feel confident that they are somehow to blame.

if you still have media .... sterilize it. and call a redo .... or just unpot ... sterilize the media .. and replant when it cools off

the soil is sodden ... is there drainage in that pot?? .. not many dormant plants like icy cold wet roots ....

where are you lily .... i am surprised you are doing this in z5 ... this time of year ...

why is the plant not dormant ....

isolate plants in different locations while you repot .... ken

I've seen root aphids a number of times but never any that lacked the waxy white coating similar to that on mealybugs. See https://www.google.com/search?q=root+aphids+site%3Aedu&ie=utf-8&oe=utf-8

And if they are root aphids, I suspect they were on the 2 plants prior to the re-pot. (In that case, I would discard the failing plants because such beasts are challenging to eradicate.)

Unless, of course, you added some garden soil to the mix.

So, a question: What did you fill the pots with? Commercial potting mix or your own blend?

If commercial mix, which one?

If your own blend, what's in it?

Root aphids, Phylloxera sp.

I'm comfortable calling them root aphids. The symptoms seem to fit and they do seem to look right (at least in person). I've already discarded both plants and will have to keep an eye on the other ones that were nearby.

We used a commercial potting mix, but I can't remember which one- it was something different than normal and the bag got discarded. I think there must have been contamination of the soil at some point, because the 2 plants were definitely thriving before we repotted. I suppose it's possible that they had a small infestation and then the stress of being repotted allowed the aphids to get the upper hand...but I tend to believe it was the soil, since it was also contaminated with fungus spores.

Thanks for the help

The "root aphids" I know are Pemphigus species. See https://www.google.com/search?q=root+aphids+site%3Aedu&ie=utf-8&oe=utf-8

So much for common names.

I'm frustrated comparing OP image with Phylloxera, especially when Phylloxera species are described as having a waxy coating. I don't see any hint of that in OP's image.

In any event, getting rid of root aphids is challenging. If the plant is in the ground, there's limited potential for active biological control.
If 2 of your divisions are infested, it's likely some, or all, of the others are also infested. You haven't seen them as yet because those populations are currently minimal.

For root aphids, the best management strategy is to prevent their access to your plants.

Perhaps a wise choice is to replace your divisions with fresh, clean plants from a different source.

Good luck in whatever you decide to do.

Okay; here's a likely answer: mites which are predators of fungus gnats and more.

These match the OP's images well.

See https://www.planetnatural.com/product/fungus-gnat-predator-entomite-m/

They look like hypoaspis soil mites which are a beneficial creepy crawler. I checked mine out under a microscope to be sure.

I found these bugs in the soil in the pots. Can you please let me know if this is harmful? Thanks.

I thought it was a new type of spider with a white belly, I can see them crawling on top of the soil of my saga palms that I have in planters. What can I use to get rid of them?

Those are hypoaspis miles aka predator mites and they feed primarily on fungus gnat larvae but will feed on springtails other mites

They are beneficial insects and your wise to leave them if they're there and in numbers then they're eating something you don't