It is hard to say what they could be, if you have a magnifying glass to get a closer look would be helpful. It's a yucky feeling knowing something is enjoying the beauty of your orchid.
The way I look at it if they invade our space and they don't help with the mortgage payment spray it with soapy water and an insecticide and they are good to go away. I like using Bayer 1/2 the recommended "potion"
If they are aphids malathon is a good one to use, but I have not idea of a formula.