Strange markings on vanda leaves
 

here is what I discovered on the underside of the two leaves on vanda insignis:

http://1.bp.blogspot.com/-7U_D1Wqjzd...nda_leaves.jpg

Closer view:

http://4.bp.blogspot.com/-qcxWBYm__c...vanda_leaf.jpg

As you can see I cut off the leaves, here is the location of where they were on the plant - the are not the oldest:

http://4.bp.blogspot.com/-nlPOAzryA_...a+insignis.jpg

What could it be? And should I throw away the plant?

Thanks a lot.

Just a little nibble damage from a pest, probably a snail from the look of it. I wouldn't have cut the leaves off, but no harm in being cautious. A general rule that doesn't always apply but is still good, if the spot isn't spreading it is old damage and not infection. One exception to that would be "Thai Disease" which I forget the proper name for (my apologies to the Thais who have done so much good for the orchid industry), which appears as eye shaped black or brown spots on either the top or bottom of a leaf, usually whichever is facing up. When this fungus is "in bloom" it feels distinctly rough to the touch. Leaves with this should be immediately removed and destroyed. It is a relentless disease. Hate it. Sorry for the irrelevant rant. Your plant should be fine. :)

According to my quick googling, Guignardia is the name of the beast that causes this.
see also
http://www.staugorchidsociety.org/PD...ai-Disease.pdf

Here in South Florida, almost every vanda you see will have some of those brown spots on the leaves. It's usually caused by a leaf spotting fungus. That type of fungus won't kill the plant and the leaves do not need to be cut off. The spots won't go away but spraying with a wide spectrum fungicide can keep it from spreading.

Yes that's it!

Thank you for the advices, I am glad I don't have to throw away the plant. That would be hard to replace.
It was living in the orchid tank with high humidity, so fungus is highly possible, although few of my other vandas are there too and don't have this problem .
I will keep it out of tank for now and see how it goes.
Thanks again.