What Jeremy said is good info, and since I've already replyed to another post earlier with these links, and was thinkin about them, I figured I'd post them for you too. There's info on mealies, and pretty much any other orchid pest, or disease there is.... So, this will be a good thing to bookmark for future reference too
(these will also help if it's more than one plant, and you wanna take "chemical" action, but also lists non-chemical means of eradication, like what Jeremy suggested)
http://www.houstonorchidsociety.org/...ySueBottom.pdf
There are two charts in this PDF, that you can't read all of, so here's the individual links to those as well:
Pesticides:
http://www.staugorchidsociety.org/PD...rchidPests.pdf
Fungicides & Bactericides:
http://www.staugorchidsociety.org/PD...idDiseases.pdf