Rocky Mountain pine / Epps beetles and dormant oil spray

As many of you know, these beetles are killing a lot of pine trees out here in the western US. I lost one of my pinion pine trees last year to them. I was told that you can spray in the early spring to ward off new infestations before they have a chance to do their damage, but by the time you notice any damage it is too late to save the tree. Does anyone know if a dormant oil spray would be effective against these beetles, or should I wait until later in the spring and spray my other pines with an insecticide like Sevin or whatever? Thanks, Gary
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