Beasties

Can't seem to remember to photograph them.
I often have two plastic mushroom boxes one inside the other. The top one with holes and the soil. I keep finding what looks like tiny white maggots swimming around if there is water in the bottom one or jumping round if it's dry. Tipping the soil out and they are in the bottom layer of the soil. Any ideas? Thanks cc

Fungus gnats https://www.rhs.org.uk/advice/profile?pid=804

Thank you