I have been cutting beetle kill Lodgepole pine almost exclusively for the last 4 years, and I always cut in the fall to burn that winter. To do it successfully though, I have to make sure I only cut the lodgepole trees that have been dead for a long enough time. They will season while still standing, but not all of them will be standing long enough.
There are two telltale indicators I look for before I start cutting are
Gray needles: If the needles are green then obviously the tree is not even dead, and even if the tree is dead and the needles are orange then the wood will still contain plenty of moisture and will need some seasoning time after being cut and split.
Vertical splits in the trunk; This is a great indicator that the tree has dried significantly, and actually one reason that pine beetle kill dries so well while standing dead, If you look carefully the old dead trees (that have gray needle) you will likely see vertical cracks running the length of the trunk, this is caused by shrinkage of the wood as it begins to dry, just like splits in a stack. These cracks can be quite wide, and once the cracks develop it opens the rest of the trunk to the air and the rest of the tree can dry that much better. It is also why beetle kill lodgepole pine trees make poor quality lumber, the way the wood dries it has too many large cracks in it.
So if you are cutting beetle kill lodgepole pine and the needles are still orange, then it will definitely benefit from some extra seasoning time. But if the stuff you are cutting has large vertical cracks running the length of the trees and the needles are gray, the wood will likely be just great for burning right away. Of course a lot depends on the climate where you live.