I have a tall, old Douglas Fir in the back yard. Over the past few years the City has over-zealously sheared off branches from the one side to protect their wires. Also over the years, I've noticed little piles of sawdust at the foot of the tree. About 8 years ago there were ants in the tree and I took the piles of sawdust to be related to their presence but for at least 5 years there has been no sign of ants. Lately large sheets of bark have fallen off the lower trunk. Looking at the inside of them, I wonder if they show signs of beetles. I'm including a photo (with a few wood bugs lurking). The tree has been a heavy cone producer for a long time but this spring I've noticed not the usual green tips at the end of the branches but instead a cluster of beginner cones. Again see photos. Should I be concerned? I've had the tree looked at in the past by the same arborist and he believes there's nothing to worry about but I feel I should get another opinion. Any suggestions for a specialist?