Your Schefflera has a scale insect infestation. Mix a solution of 5 parts water, 1-part alcohol, and a squirt of liquid dish soap. Then, spray all leaf and stem surfaces until they are dripping wet. It is a very messy task, but unless you get complete coverage and make direct contact even with the ones you cannot see, the survivors will reproduce, and the infestation will return. Be sure the solution runs into the crevices where leaf stems attach to the main stems.