Question
My orchids have developed raised brownish orange spots on the leaves. There also appears to be sticky, slimmy substance on the leaves. Never had this problem before. Any idea as to what the problem is and possible corrective actions?

Answer
Barbara, it is likely that your plant is infected with brown scale.  This is an insect commonly found on orchids, so named because the adults form a half scaly shell.  When there are adults, there are also "crawlers" which are more difficult to see because they take on the color of the plant.  The crwlers suck the plant juices as they crawl along  the plant.  The excess plant sap, which contains sugars is sticky. Where there are adults, there are crawlers and eggs. While many are visible, most are not.  They may be present in the potting mix, under the leaves, on the back side of flowers, etc..

Here are my recommendations: Isolate your plant to minimize the spread to other nearby plants; 2) soak tissue, Q-tip, cotton ball, etc in rubbing alcohol (70% isopropyl alcohol), then use it to remove all adults and crawlers by rubbing them onto the tissue or cotton; 3) purchase a systemic insecticide effective against scale and make a drench in enough solution to be able to submerse the entire plant (be sure to use chemical gloves); 4 remove the plant from its pot, thoroughly rinse off the roots and submerse the plant in the systemic insecticide for half an hour.  You may clean and also submerse the pot if you plan to use it or use a new pot).  Discard the old potting mix into a sealed bag and toss in the garbage.  Repot in frsh orchid potting mix after you have soaked it for an hour in water (it contains fir bark which repels wter and the soaking will rduce this repellancy).  After repotting, you will want to keep the plant outside for several days as the insecticide likely will have an unpleasant odor.

You could get by without the entire treatment but it is likely that you will be fighting an ongoing battle with this scale insect.