Then there are differences in soap, concentration and or species.
Well, I completely agree with Leatherback.
I have been using insecticidal soap day, night, sun, shadow, winter, summer, and haven't killed a single tree (except the JBP upside down as seen above).
As for the mix, I have been using:
1 liter water + 100ml isopropyl alcohol + a splash (generous) of dishwashing soap.
It works every time, specifically well for spider mites.
