Question
Hi, my ctenanthe plant gets tiny sticky spots on the underneath of the leaves which then seem to create a dark tiny spot on top of the leaf, I can see no bugs. Doesn'tlook the best.

Answer
Margarita, I can only guess at your problem with your Ctenanthe -- because I'm not clear about the symptoms.

Tiny, sticky spots on leaves are often the work of Aphids -- see the Doctor Optimara discussion(http://www.optimara.com/doctoroptimara/diagnosis/aphids.html) of this problem.  Although the Aphids in their illustration are large and obvious, aphids are often small and can be hard to detect, the only symptom being the "honeydew" -- aka "tiny sticky spots" -- on the leaves.

But you describe a "tiny dark spot" created by the sticky spots?  I'm confused.

If this is a bump that you are talking about, it would fit the description of a differentpest, called Scale.  Some Scale insects secrete their own sticky substances onto the leaves. We don't always see Scale; males are clear and females hide inside the dark round bump, where they lay eggs and wait for them to hatch.

In either case, there is a treatment that will put your Ctenanthe on the road to recovery.

Organica makes a Neem-based spray(http://www.organica.net/consumerkneem.asp) called K+NEEM INSECTICIDE.  Many people advocate washing or spraying plants with insecticidal soap, but this will probably not work if you have a Scale problem.  You can buy it in many garden centers and all over the internet.

I don't believe in use of Sevin, Malathion, Bonide, etc., especially for houseplants.  These are dangerous chemicals that no one should handle.  There is also no reason to use them since Organica and other companies make insecticides that are just effective -- sometimes they are even more effective.

If you have a garden outside as well as inside, I can't recommend Ladybugs enough.  Sprinkled on your Ctenanthe, they will make mincemeat of any Aphid or Scale, permanently.

If you can give me more information about the symptoms, I would love to hear them.  Otherwise, keep me posted.  Thanks for writing.