Answer: I'd guess the pests are whiteflies. They're difficult to control, but it's important to get the upper hand before they infest any other houseplants you might have. Whiteflies are attracted to the color yellow. You can purchase or make yellow "sticky" traps from yellow cardboard smeared with petroleum jelly. They fly to it and get stuck.
Next on my list would be an insecticidal soap spray. The insecticidal soaps are made from plant-derived fatty acids and target soft-bodied insects. There is really no effective chemical spray for whiteflies but researchers are working on it. I'm afraid you'll just have to keep after the problem on a regular basis until you get them under control.
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