Cat leaves Turing yellow....pests?
 

Cat leaves dying one by one.....small black objects near base...any thoughts

Another pic
 

Leaves completely yellow

It looks like one of the older leaves dying off - part of normal lifecycle. The plant looks quite dehydrated - does it have a good root system? The plant will take water and nutrients from the oldest growths if it doesn't get enough through the roots, so this process accelerates the die-off. Get some KelpMax and help it grow some healthy roots.

I don't think this has anything to do with the tiny black bugs, but bugs will attack a plant in distress sooner than a healthy plant.

Two or more of the pbulbs looks discolored with rot of some sort.

Not that I know much, but from what I know about cats, they like it pretty dry, and need to be very quickly watered. The rot makes me think that they are too damp all the time. If that is the case, get rid to the medium and dry the roots out. You may need to cut off those rotten p-bulbs, and get some new roots growing like Al Toranto says.

I agree that this looks like some sort of bacterial rot that is spreading. You may be able to salvage part of the plant if there is a healthy section that can be separated by severing the rhizome (cutting into green tissue between the rot and part of the plant you are trying to save). Once the pseudobulbs start turning brown, they are done for.

You can distinguish between rot (pseudobulbs turning brown from the base/rhizome, spreading up; process relatively fast) from normal old age (leaves die first, pseudobulbs usually going brown from the top down; process is slow).

This is rotting. I feel it is too late to save it. Once in the rizome the plant is doomed. Sorry. It was kept too wet and the roots died. This is why it looks dehydrated.

looks pretty hopeless to me, sorry! take it out of the medium, trim out everything dead or dying, and see what you have left....to me, it looks like the rhizome is dead...if so, it is all garbage, you cant fix that!...if there is any green rhizome with a leaf/psuedobulb that's still green, you might be able to sphag and bag it and get a new shoot started...good luck!