Last year I had a jarring experience driving through some of the agricultural land near the Salton Sea en route to Bombay Beach coming down from JTNP, taking back roads.
The general region is desert, water and food is scarce, but through this agricultural zone there's this dense pocket of food and water on the surface.
I was in a Miata with the top down, and the amount of chemicals they were using to keep the pests/insects away from this lush green oasis in a land of nothing was noxious. I hadn't exited my car, just drove through these fields on the farm roads, and it left me feeling sick with a headache and nausea well into the next day.
Of course I didn't encounter a single insect, spotless windshield.