Congrats on the award. Thanks in advance for any help you can give me. Your ficus trees have a common problem that is easily remedied. There are several organic methods that work well. Your trees probably have either aphids or scale insects .
Scale insects are particulary good at hiding.
If the problem is severe, you should first try to physically remove some of the insects. For aphids, you can blast them off with water spray. If you look at your trees and decide that is way too big a job, then go to the next paragraph. I have this same problem with my lemon tree. I have found ultra-fine horticultural oil to be the most effective control.