Question
Hi

One of my Phalaenopsis keeps getting what I can only describe as very small brown risen spots on its leaves (mainly the underside).  When you remove them they have a very sticky liquid that comes out of them.  Have you any idea what it may be and how I can get rid of them.

Answer
Good day Mary. From your description, I believe the brown risen spots is an insect referred to as brown scale.  The scale insects feeds on the plant sap and the plant sap is loaded with sugars--hence the stickiness.  Scale insects have a life cycle which includes a crawler stage and an adult stage.  In the crawler stage, they are more difficult to spot as they don't have their brown shell and are colored so as to match the plant tissue color.  In the crawler or juvenile stage, they move about the plant sucking sap until they mature and develop the brown shell which is quite visible.  To begin with, I recommend that you remove any insects you can see using cotton or a small cloth soaked in 70% isopropyl alcohol (ie rubbing alcohol). You will need to repeat this process once each week until you see no more signs of either crawlers or the adult shell.  The reason to repeat is that there will be eggs present that will continue to hatch and there may be insects hidden which won't be visible until they crawl out from their hiding place.  After this initial step, you might also wish to apply a systemic insecticide that will kill the insects as they suck the plant tissue.