A. If you search the Internet you will see all sorts of homemade remedies recommended by different people. These include diatomaceous earth, repelling them with garlic or hot pepper sprays, and even oils of mint and rosemary. The problem is they have no documented history of working.
Until we have some definitive answers about what is working and not working and still safe enough for food crops, we are left with either trying products recommended on the Internet in a “trial by error” method or using products with a known history of success.
I frequently look at the University of California IPM (Integrated Pest Management) recommendations for insect control. They publish information that works but unfortunately many of the so-called “organic” methods have not been tested adequately.
Pyrethrin sprays come from “organic” sources and some sources are manufactured. Read the label. The label makes this distinction.
There are “synthetic pyrethrins”, some called pyrethroids, labeled for controlling this insect pest on pistachios. They do work if the directions on the label are followed. Synthetic pyrethrins are designed by chemists to “mimic” natural pyrethrin’s toxicity. But they are synthetic and may or may not be as “safe” to use as pyrethrins.
I usually do not promote recommendations found on the Internet that have not been shown to have a history of success. If I do mention something without a history of control, I follow it up by mentioning so.