I'm thinking you may have spider mites or aphids. Search around on the undersides of the leaves for webs and maybe some tiny red dots on or near the webs. Also look for sucking insects at the junction of the leaves. Here's a converstation you might find helpful.
Q: My schefflera trees are about 18 years old. I keep them indoors during the winter and outside during warm months. This winter a "sticky" liquid is dropping from the trees onto the floor. I cannot see scale or other pests. Can you offer suggestions on how to treat the leaves to keep them from dropping the sticky liquid? They get good light, afternoon sun and I do not over water them. One tree is 10 feet tall and the other is 12 feet. I would not like to dispose of them, but if they have an untreatable disease, then I will have get rid of them. (E-mail reference, Augusta, Ga.)
A: I suspect that you may have spider mites doing some feeding on the leaf undersides. They are about the size of the dot at the end of a sentence and blend in quite nicely with the green foliage of the plant. Look for little webbing on the leaf edges. Try taking a damp sponge and wiping the upper and lower surfaces of the leaves off. This will remove any mites present. Do this every two weeks, especially during the winter months when the interior air is so dry. It wouldn't hurt to mist the foliage with distilled water either on a regular basis, like three or four times a week. If this doesn't stop the sticky dripping, then I'd suggest getting rid of it. In the meantime, place a tarp or old tablecloth under the leaves to protect the flooring.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.