Hey Growmie,
Since these aren't regular aphids the normal treatments aren't very successful so here are a few suggestions on dealing specifically with root aphids:
Natural predators: For outdoor plants, predators such as birds feed on aphid eggs, parasitic wasps also attack the eggs, and ladybugs eat aphids on top of the soil.
Beneficial nematodes: Introduce beneficial nematodes into the soil and they will protect against a number of soil-borne pests including root aphids, without harming beneficial like earthworms. Nematodes can be used on indoor or outdoor plants.
Neem oil: While it won’t kill the root aphids, it can help keep an infestation from spreading.
Avoid spreading infestations: Be especially careful when relocating or disposing of infected plants to not drop soil. This can lead to spreading the infestation to other pots or nearby plants, or tracking soil on the soles of shoes to other locations.
Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.