My hibiscus has lots of yellow leaves and black tiny bugs. I have sprayed with different insecticides and it seems to get worse.
Certified GKH Gardening Expert
It may be aphids. This article will help:
It might also be several other bugs, but aphids are the most common. Regardless of the bug, all of the common pests on hibiscus can be treated with neem oil. Here is more information on neem oil: