Question
Hi, I read another question about a damaged tree and it said Connifer Beatles may be the cause. I have a very old Ligustrum tree and something is eating the main trunk and a few branches.  I can find NO signs of a bug and my bug man who comes every month could find no signs of tunneling so he ruled out termites.  But something is causing damage and eating my tree.  The leaves are still green, producing new growth and it flowered this spring but I have 2 main trunks and one is almost eaten in half now.  I don't see any holes where anything has burrowed in, no signs of life whatsoever, no growth (fungus) and no sawdust at the base, but the bad spots have been turned into sawdust.  I don't know whether to spray insecticide or call a tree person?  I really hate to lose this tree b/c it gives me so much shade on my courtyard!

Answer
If the foliage is green and full the tree is healthy. It sounds like the wood in the center of the tree is decaying and the tree may have some hollow places in the trunk. The living part of a tree is just under the bark and the bark protects the cells from decay fungi. When there is a wound to the bark decay fungi can get into the woody cells and start the eat away at the cells.  The woody cells are dead cells and not associated with the healthy of the tree except for strength.
Trees can and do live many many years with their trunks completely hollow. Trees have the capability to seal off the decay fungi and slow the growth of the decay. IF the large limbs start to break off and the end near the trunk is decayed or hollow then the tree may have reached a point that it could be a hazard. And then it is only a hazard if it is locates near a structure that could be hit by a falling limb. Yours sounds a long way from that stage.

I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter and water it in  good, or wait just before a rain storm and fertilize and you will not have to water. This will increase the health of the tree and help slow the decay fungi. I would do this now and again after the leaves fall in the Fall.