OK, I'm curious. In the US, do you have ants that damage the orchids?
In Spain and in the UK, we don't. My greenhouse has a resident population of ants, and they harvest the honeydew off the orchid stems and shoots. They do no damage that I can see, and ensure that any bugs that land on the plants are given short shrift.
I wouldn't dream of killing them. We have a deal, the ants and I. They stay out of the house, and I don't kill them in the garden.