I thought these were pieces of dirt until some of the leaves started looking sick. I’ve never seen anything like critters before.
Are they winged insects? Could be fungus gnats.
I used to get fungus gnats using soil indoors. Coco coir solved that problem. These critters are on my coco coir outdoor plants. They’re after my tomato plants too. I used Neem oil on them today. Hopefully that’ll take care of this.
Lemon oil, peppermint oil, hydrogen peroxide, make a solution up of one of these with water spray plants down next time switch to one of the others and continue to alternate between them if the neem oil doesn’t do the trick