I can't seem to findn the post now, but I do know how to beat white flies on hibiscus.
One of my hibiscus seems to break out w/ white flies every summer in July. I have tried pest-a-cides but they don't seem to help.
I got really mad at the plant
and bugs one day and got a old rag out and wiped every branch w/ a damp cloth. Some of the leaves came off but so did the bug. The leaves are coming back quickly and the bugs aren't. We spray it down maybe every week or so w/ water/soap mixture after that and then just leave it alone.
Hope that helps!