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