Looks like thrips larvea, not bad if taken in time.
You already have yellow sticky stuff for adult thrips, but larvea are living in the soil.
Flushing the soil is an options, not my favorite. The other is increasing runoff every watering.
Looks like a thrip infestation. The adults will be trapped by the yellow sticky traps but if the larvae are in the soil you'll need to get some Imidacloprid, which is used to help get rid of soil insects, you can order it online.