Holes in Phalaenopsis

[kate887]

I've had my Phalaenopsis for well over 7 months and its been doing just great! However, recently my orchid developed some pretty nasty holes. They are only on one leaf, the others are just fine.
Here's a photo of the leaf: http://twitpic.com/11fnj6
I am not sure what to do. Should I purchase pesticides? Should I tear off that leaf?
I had a new roommate move in a few months ago, and she put her orchid on the table next to mine. Hers had some smaller holes when she brought it, but nothing like the holes I have now. I am not sure if this is related?

Thanks in advance for any suggestions!
Kate