Hi Tom!

The tube-like formations are sawdust tubes pushed out by ambrosia beetles as they bore into your tree. The beetles introduce a fungus into the tree, which clogs up its xylem (the water and nutrient transport system). The beetles are not necessarily a death sentence. When numbers are low and a tree is fairly healthy, a tree can recover.

You should have a certified arborist assess the tree to determine the extent of damage, to verify that ambrosia beetles (of which there are several species with somewhat different life cycles) are in fact the primary culprit, and to determine if any other stress factors are causing the tree to be more vulnerable to attack. Several, though not all, species of ambrosia beetle attack trees that are already experiencing stress from overly-wet roots, drought, physical injury, or another environmental factor.

Jamie