What do you treat gall midge on hibiscus with?
Certified GKH Gardening Expert
It is difficult to control or treat these, as they usually reside within the plant. The best method of treatment is to remove any, and all infected parts of the plant. Now once thing you can try, as plants can take up some pesticides through the roots, is rosemary oil! Just add a teaspoon to a gallon of water, and water in with this. There is no guarantee that this will work, but there is a great chance it will help you to control the problem easier.
Here is an article for more information on the pest: https://www.gardeningknowhow.com/plant-problems/pests/insects/blossom-midge-in-plants.htm