I was also thinking of getting the Bayer Advanced 2-in-1 Systemic Rose & Flower Care and adding granules in the new medium, but then the Q&A section said it was not for use in potted plants. I may have to check Home Depot or Lowes to see if they have this the next time I go. I don't have any children or pets to worry about. Just curious, but what is your avatar?

I think a systemic is the best way to get rid of scale. It speeds things up to clean the leaves of all visible ones, but there will surely be more that are eggs, or you just can't seem them. All of them want to suck the life out of your plant so by giving it a systemic, they will be drinking it and therefore everyone of them should eventually get a dose of it and die.

Gin mentions the Bayer product as a drench, so maybe you can find a liquid form rather than the granules. If you are in a large enough city for Lowes and Walmarts I would think there are seed and garden centres that carry more products such as Merit or a liquid form of the Bayer systemic.

Imidacloprid
 

The Bayer product contains imidacloprid. You can get this as Merit WSP (Water Soluble Powder) and various generic forms but it will cost you.

Imidacloprid, Imidacloprid Insecticide, Imidacloprid Pesticide, Imidacloprid Products - Free Shipping

I have this form of imidacloprid:
Dominion 2L, Dominion 2L Termiticide Insecticide Concentrate - Free Shipping

Here are some pyriproxyfen products. I have the Nyguard.
Pyridine, Pyridine IGR, Pyridine Pest Control Products

I called up a trusted vendor (not where I got this orchid) and had a lengthy lesson on scale and treatment. Here's what I've learned so far:
* The scale infestation looks worse after I sprayed the Malathion, because the spraying upset them so they are coming out from their hiding places (medium, within the dried areas of the pseudobulbs, etc).
* Neem oil will not do much to help me when the infestation is this great. I will need something stronger.
* Scale also lives in the medium, pseudobulbs dried sheaths, leaf crevices where I can't see in addition to the front and back side of leaves.
* An infestation this great will mean I will have to keep up with spraying and treatments for at least 2 months. Even after 2 months, I will have to keep a watchful eye in case any survive. Scale is like mice. Once you see one, it means you have close to 10.

Recommendation:
* Use Bayer Advanced 3-in-1 Insect Disease & Mite Control at full recommended strength and spray once a week.

While he personally has not used it as a dunk, I am going to mix the recommended bottle dilution in a bucket and dunk the whole pot to the top of the pseudobulbs for about 5 minutes, let it sit for about 20 minutes to let it soak in and work its magic. Afterwards, I'll soak in water and do multiple drenches to wash it out. I will follow this up with spraying the rest of the leaves.

I'll do the dunking once a month and the spraying once a week. Hopefully this will work.

I used the granules on a Phal. as a test . Did not seem to hurt it at all ,but it is in moss which keeps the granules from washing thru ..

I had a L tenebrosa that drove me nuts with scale infestation. I would treat and it would return. I would treat and it would return again, even worse. It was a large, older plant. I spent just about a year and finally gave up and tossed it.
I don't why this plant was susceptible? I think it was stressed from the first bout and never regained momentum. I do believe that stress has much to do with pests, diseases and susceptibility.

I think you are right seems once they have scale it weakens them ..

I can't really remember how I disposed of the dunk. I worked on my plants out in the yard far away from my other chids and tropicals. I don't really remember about disposal but I probably sprayed it on the mulch in the area where my plants became infested. All the pots of my infested plants made direct contact with ground covered mulch. Growing them in that fashion was like an invitation to bugs, but I didn't know that at the time.

DavidCampen-thanks for the info. I am going to look into esteem. will update the results.

My collection got a moderately serious infestation of scale after a period of neglect due to a family members serious illness (5000 plants 2500 of which are cymbidiums) The size of the collection put me way past management by home remedy - I had to get serious or even the Bayer Tree and Shrub was doubtful. The insecticide of choice for me was "Safari". I used this in rotation with several other insecticides Orthene, diazinon(off the market) and Melathion. The rotation was a new spray at two week intervals. After the infestation appeared under control I switched to a monthy rotation of "Safari" and "Distance". The remedy was effective but if you look "Safari" and "Distance" on Google then find a source and price you will get "Sticker Shock". Whatever you use you should rotate the sprays according to the instructions on the product. Continually using the same product may allow the scale to develop an imunity to it.