spray them with a pyrethrin based soap. safers soap. you can buy it concentrated or diluted.
you can also use neem oil or use both .
Safers Soap and Neem Oil
they're not harmless they will halt the growth of the plant completely
if there are enough of them. they tend to feed on the growth tips
in large numbers.
spray it once a day at night until they're no more.
ladybugs work better indoors or in greenhouses where
they can't fly away.