Identifying ficus whitefly vs common planthopper

Ficus whitefly (Singhiella simplex) ID Naples, Florida: I have had several people drive all the way out to our Extension office with an insect they thought was the ficus whitefly. It has turned out to be a planthopper. There are several planthoppers you may find on ficus. They cause little damage, a NBD, no big deal bug. They can easily be separated (now that you can see them side by side) by their size, the whitefly is a little over 1 mm long from head to wing tip. The planthopper is about 6 x larger. Plus the ficus whiteflies have their wings flat over their backs (this one was frozen & was thawing so its wings are a little disheveled); whereas the planthopper wings meet over the top like a roof peak.

The ficus whitefly has a yellow body and two smokey gray bars on each front wing. The first pair of bars is near where the wing is attached and run parallel to its body, but the second pair, about midway on the are aboiut 2X larger and are at right angles to the body. There is another whitefly on ficus (Tetraleurodes fici) but it is larger (on penny) than the ficus whitefly and doesn't have the wing makings as described nor does it have a yellow body. It doesn't tend to build up in large numbers nor cause damage, a NBD kind of whitefly.

What to do with sooty mold on coconut trunk???

I have a call from a consultant dealing with a man who owns an island in the Lesser Antilles. Due to a whitefly or/and aphid pests (pests are being dealt with) his coconut palms have sooty mold. This is unacceptable and they have tried to power-wash it off with "soap"- brand? to no avail. So they've started sanding the sooty mold off in the meanwhile!

I suggested a weak chlorine solution (10% bleach to 90% water).
Other ideas:
1. try a horticultural mineral oil (2%) without high pressure and wait a day and then powerwash lightly with water. May take several attempts.
2. The oceanside of the trunks are clean; try using ocean water with low, not blasting pressure. May take several repeated applications.

Has anyone found a one-shot application technique that won't harm the palms?
But really.....
This is strictly a case of the "perfect apple" syndrome and probably few would notice the dark shadow on the trunk. Hopefully they won't be cut down in an attempt to make the view "perfect"??