Velvet mites
Velvet mites are not harmful to plants, far from it: larvae are parasites on other animals, protonymphs are inactive, deutonymphs are predators, tritonymphs are inactive again, and the adult individuals go back to being predators. I get the impression they live off springtails in our garden.
I've only seen two red velvet mites: one with the wrong lens on my camera and so for all intents and purposes invisible, and one with the correct lens but without diopter ring of ring flash, so not clear at all:
Possibly a red velvet mite (Trombidium sp.?)
These are velvet mites without a shadown of a doubt. They're also much larger and they has the velvet mites' typical dimpled shape. I can find them any time of the year on one of the apricot trees at my parents'.
Red velvet mites (Trombidium sp.)
Unknown mites
I found this small pink mite in an outdoor plant pot:
Pink velvet mite?
It looks like a velvet mite, but I'm not sure at all. It might be a deutonymph, or it might be a pink mite.