Tranluscent spots on leaves

Hi all!

I recently started seeing translucent holes on pretty much all the plants in my garden. The only ones that appear unaffected so far are my sweet peas and tomatoes. The zinnias and peppers are the worst.

At first I thought maybe it was due to too much fertilizer, but when I started to see how symmetrical the holes are, I began to suspect something more.

I can't seem to locate any bugs or larva on the plants. There is also really no dark spots etc suggestive of fungus/bacteria. I do Iive in a Japanese beetle endemic area, but I don't see any on the plants. What do you think is causing this?

I tried pyrethrin spray and it hasn't gotten worse, but I am leaning towards treating with a systemic. Any suggestions?

Thanks so much!