Imidacloprid is a widely used, effective, relative safe insecticide. A downside is that it is rough on bees. However, with your limited use of it, I wouldn't worry about it.
But, if you are, you could make your own aphicide.
https://proshieldpest.com/tobacco-bug-spray/
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Tcoat could send you a supply of used cigarette buts, you could boil up for your concoction. Ol Tcoat and I have been using nicotine for years to control garden pests. We use the "dusting - smoking" method of application.
Set up a lawn chair in the garden and puff away on a few cigarettes each evening.
OK, that reminds me of a back in the day pesticide research story. When I was a research rep for a large manufacture of pesticides, I had a tech rep down in Arizona that called me and declared that he had discovered a new use for one of our insecticides, as a miticide, and ask me to come down to Arizona to document his discovery.
Although it was July and temperatures well into the 100s, I drove down to appease him. I met him one day the next week and we went out to this grape vineyard where he demonstrated that Imidan kills mites. He fired up his CO2 sprayer, filled the tank with "hot" water that come up from a deep well, added some Joy soap (to act as a surfactant) and the Imidan.
He then proceeded to spray some grape vines that were almost dried up from moisture stress and loaded with aphids. Yep, sure enough, his concoction zapped the aphids!
NOW, I said to Tom, how about setting up a control, using the same situation but without the Imidan. He did, and low and behold the aphids were also killed -
I had to explain to Tom, that the combination of 90 degree water, plus 110-degree air temperature, plus the surfactant (soap) applied to stressed out aphids on moisture stressed vines, actually killed the aphids.
Needless to say, he was rather disillusioned and apologized for having me come all that way down to Yuma. I said that was OK, he just needed to take me out to the best restaurant in San Luis (just across the border) to get some
real Mexican food. -
THE END