I think tropical hibiscus is what whiteflies live on.
Had them in my green house and they took it over. I
no longer have the tropical hibiscus, only the hardy type.
Norm

There are various natural ways to control them. See link below. I used the yellow sticky traps with some success. Didn't have hibiscus, though.

Here is a link that might be useful: White Fly control

Laura, I have used the yellow sticky traps inside during the winter, but not outside.

Also, I think I remember someone last year indicating that the white flying insects were something else besides whiteflies (Oriental something, maybe??). Anyone else remember?