Root aphids

I have been cleaning up my Auricula seedlings and far too many of them
have bad infestations of root aphids. Has anyone ever found an effective
insecticide? At the moment I am washing all the compost off the plants
in a Horticultural soft soap solution. The aphids are covered in a wax
which stops normal insecticides from reaching the creatures.
HELP!!!!!!!!!!!!!!!!
HELP!!!!!!!!!!!!!!!!
0