Thanks to Ray and Jeff. I've ordered Inocucur, Phyton 27, and a horticultural oil (just in case it's false spider mites). Given the extent of the infection and how quickly it's spreading, I'm going to go straight to the Phyton on the phals. The paphs, oncidiums, and milts will probably get the Inocucur treatment.
I fear I've already lost a few of the phals, but I'll see how it goes.