Question
I have a schefflera plant that I've had for 10 years. over the past month or so I've noticed these little brown rough feeling spots forming on the top and underside of the leaves, on the stems and on the branches of the plant. Some of the leave are very shiny and kind of tacky. I've had a couple of the branches that have lost all their stems and leaves. I've had spider mites on it once a few years ago but this doesn't look like the same thing. I'm at a loss on what to do for it. Can you help?

Answer
Hi Tim,

These are typical symptoms and signs of a scale insect infestation.  The brown spots that you see are the adult insects attached to the plant's leaves and stems.  They can be very difficult to remove, but with a bit of elbow grease and some mild soapy water and an old toothbrush, you can remove them.  (Obviously if you have a large plant, this can be very tedious.)  From time to time you may see some small white flecks of cotton-like appearance.  These are the juvenile insects, and they can be easily removed with 70% rubbing alcohol (isopropyl alcohol) on a cotton swab.  

Scale insect populations are normally controlled by their natural predators when outdoors.  When grown indoors, these predators are not present, so the scale insect population explodes.

The sticky residue that you feel is the "honeydew" produced by the insects, and it is has high contents of sugars that are produced by the plant.  If these residues are not removed, they can provide the nutrient source for other fungal organisms.

If you have tried all the above control measures and still have a problem, there are horticultural oils that can control the scales by "smothering" them in the oil.  These oils are particularly sensitive to temperature, and great care must be used to apply these oils without further affecting the health of the plant.  

These infestations are common and usually a nuisance, but when the infestation becomes severe, the plant can defoliate completely.