Q.Gardenia Bush
My bush is about 10 years old. It blooms like twice a year, but today as I sprayed it, lots and lots of white flies flew off. Also, the blooms are full of little black bugs. This is always the case. I have never treated the bush or fertilized it. I did cut it back once because it got so big. What can I treat it with to kill the flies/bugs without harming other flowers that I planted close to the bush.

Certified GKH Gardening Expert
These are whiteflies and this article should help: https://www.gardeningknowhow.com/plant-problems/pests/control-whiteflies-on-houseplants.htm
I would suggest using neem oil to treat the plant. It is effective at treating these pests and quite safe to use. Here is more info: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm