Hmm very annoying.
Everything i search online always recommends spraying them with soapy water, so it's gotta work.
if you want a more serious approach get some Diatomaceous earth food grade.
just don't breath in the dust or get it in your eyes.
https://www.nhs.uk/conditions/silicosis/
nhs says it would take years of exposure but since your dealing with such a concentrated amount don't be stupid and risk breathing any in when you apply it.
you can apply it wet and it will kill whatever touches it once its dry.
or you could spray your plants with a mist of water outside and then dust them with it after to help it stick to the plants.
it's not toxic to humans or animals, but if breathed in can obviously cause problems.
pool grade is toxic to humans though!!!!!
technically I guess if you wanted to be really cautious you could just brush it directly on to any affected areas of your plants, also you can sprinkle it on the compost and anything walking in it will die.
it does nothing if its wet but once it dries out again it will cut them up and dehydrate them
even cockroaches will die if they come in contact with it.
it's basically a bag of these that looks like powder to the human eye
it won't harm your plants or the roots.
personally I wouldn't touch it with my hands even if its safe.
people spray it on fruit trees to kill catterpillars etc its totally safe just dont breathe it in and you can rinse it from your plants once the infestation is gone.
I coated my pantry cupboard floor with a fine layer of it, kills any silver fish, beetles, spiders etc that find their way in there