There are still ficus hedges defoliating and dying from ficus whitefly attacks in the Naples area. The good news is that Dr. Doug Caldwell with the UF/IFAS Collier County Extension reports there are increasing numbers of good insect populations that kill the ficus whitefly, specifically a small parasitic wasp (a newly discovered species, yet to be named), green lacewings and blue lady beetles.
Because the ficus whitefly populations are being reduced naturally by these three beneficial insects, do not spray foliage with pesticides. This way, those good bug species thrive and suppress the whitefly. Instead, a soil root application of systemic pesticide may help.
The ficus whitefly populations get busy reproducing in late June through July. There may be ficus leaf drop at other times, but it is due to earlier feeding damage. A situation where no treatment is applied is best, but if you feel you need to apply a pesticide to save the hedge, you should apply the pesticide to the soil when you first see adult whiteflies in mid-April to mid-June. Remember it takes several weeks to translocate into the foliage.
If you feel your hedge needs a pesticide application now due to large numbers of whiteflies, use a soft pesticide such as horticultural mineral spray. It will control what it contacts and there is no significant residual chemical that will harm the good bugs later.
For more information, please contact the University of Florida Extension Office at (239) 252-4800 or see a fact sheet at http://tinyurl.com/ha82g7y.