Go to a garden center or even Home Depot or Lowes in there chemical section and get some ultra light oil. You mix it 1 tablespoon per gallon of water and spray it all over the plant and flowers. You can also add a drop of dish washing soap to it to help it stick to the orchid.You then do spray it every day for a week and then every few days for a couple of weeks and then once a week for a few more weeks. Just don't put it in direct sun after it gets sprayed as it could then get sun burned. I would also repot the plant as many times the mealies are in the potting mix. When you have it unpotted spray the roots that one time and then repot and don't water right away. That holds true with any of the sprayings as it it smothering the insects. After the leaves are dry you can water if you want or need to. I have a full greenhouse of orchids and have started doing this every month in order to keep any bugs from getting established. Pay particular attention to under the leaves when spraying. You may even need to pry the leaves apart if needed. Remember you are only killing the ones that get covered with the oil water combo.

Ok thanks:)