If you notice that your plant has oval, crusty bumps on it in colors of gray, black, and brown, you probably have what's called scale. These insects, too, suck the juices from the plant. You can already see how it is stressing this Ficus tree. It's easy to see why these tiny pests are called whiteflies. They start as tiny, whitish-green eggs found on the undersides of the plants' leaves.
Aphids are small oval insects in colors of red, green, or brown.
They spread quickly and can do major damage to your plant. A white, powdery residue or webbing around the leaves are signs of spider mites. If left untreated, they can kill the plant. Now, for small plants like this, what i have done is put this in the kitchen sink and just given it a nice little bubble bath. That seems to work really well.