White Mildew? Yellowing leaves on New Growth, Help!

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Imidacloprid is not a miticide and is said to even aid mites since it kills off any natural predators. Mita X sounds like a miticide going by its name. If you do need something stronger, Malathion has worked well for me in the past. it stinks, but I'd rather smell that than have spider mites on my orchids. Be sure and keep your plant isolated from others until all mites are gone. They will need repeat treatment to get all eggs that hatch. Good luck.