Question
Recently some of my orchids (Phal) started showing white powdery spots on the underside of leaf and down in the very center of the plant where new leaves emerge.  I can wipe them away but then the leaves start getting a sticky substance that does not want to be washed away.  If you are temporarily successful it just comes back. It seems to be spreading to all my orchids even though I have isolated the sick ones.  Is there a treatment for them?

Answer
Jackie, your description sounds very much like you have an infestation of Mealy bugs.  You will need to find an insecticide at your local garden center that is specific to mealy bugs.  I would prefer a systemic product that penetrates the plan tissue and kills the mealies as they drink the plant sap from inside the plant.  The sticky substance is plant sap that is rich in sugars and hence sticky.  You can remove some mealies by rubbing them with a cotton swab soaked in rubbing alcohol but you will not get them all this way.