Please don't forget plain horticultural oils, as well as the Neem. And you should be aware that these oils can do damage to the smallest of the predators, so if you plan to purchase and release such insects, best to do so AFTER you have done a couple of thorough applications of the oil of your choice.

I'd also like to re-emphasize that it is very important that you get these products to the underside of the leaves. I've found that improper applications can equate to a big waste of time and $.

It would be worth bringing up one of the most important factors in successful Integrated Pest Management: avoiding altogether those plants that are especially prone to specific pest problems. You've learned the hard way (as most of us have, lol) that IF you have gardenias and certain hibiscus, you WILL have a whitefly problem! These plants tempt them in to the rest of your landscaping, too.

In my mind, this means that I might allow myself ONE gardenia, rather than several, but I will be sure to position that special plant where I can get the most enjoyment out of it.

By the way, when I lived in coastal SC (8b), the yellow sticky board resulted in the death of those wonderful little green anoles. I had put some up in my greenhouses and returned the next day to find (to my horror) that the anoles would jump to the cards to get the whiteflies! I tossed the entire box away that morning. If you have the lizards where you live, it's something to think about.

An additional source of the white flies at my house is privet hedge. I don't grow it intentionally, but it is an invasive in the woods all around.
As I pointed out (I think) earlier, my experience indicates that for most years the anoles and maybe other beneficials (I never recognized any)keep the white fly population to a mild roar. Once you start spraying in earnest, you are done for. It seems to increase the population.
Also, it always seemed to me that the population was cyclic, and after an initial burst, the numbers fell off drastically. I tried to keep them off plants that would eventually go back in the greenhouse.
Lest you assume I do not have a real grasp of the situation, the time I was spraying with various chemicals several days/ week. there were so many that when you went outside they would fly in your nose and mouth.

Thanks for these comments, all your info is very helpful!! I have my yellow sticky boards out but I did go ahead and throw out my hibiscus this morning as the leaves, although healthy still were almost white on the front AND the back. I really can't believe how bad these things got! Now I will try out these recommendations/tips to save the rest of my garden. Thank you again.