What are those tiny black bugs in Gardenia bloom?
Tiny black flea like insect.
Certified GKH Gardening Expert
It could be a number of things. There are many small black insects, so from this description and no way to see them, I can't really narrow it down.
This article will help you to craft your own pest control: https://www.gardeningknowhow.com/special/organic/natural-home-pesticides-organic-garden-pest-control.htm