I have a few fruit trees (orange, lemon, lime & avocado) in pots. I've had the orange tree for about seven years. The others are new. Last year (2018), for the first time, my orange tree was infested with cucumber beetles during blossom time and never produced fruit. I believe the source of the bugs was the potting soil I used to repot the tree. I used Dawn dish detergent in water to take care of the bugs and treated the soil with a neem oil solution to kill any eggs / larvae in the soil and to act as a systemic against future infestations.

It seems to have worked fairly well. I did have some cucumber beetles this year, but not nearly as many as in '18.

Now to my question - does anyone know how long a neem oil soil treatment lasts? And is there any better treatment for cucumber beetles that is safe for pollinators and won't render the crop unsafe for human consumpton?