Question
We have about six, about sixteen-year-old aspens.  Last summer and this summer, several of them have had strange holes in the bark.  When we looked closer, there are bugs in them that appear to be digging out little splinters of wood and emptying them out of the tree, leaving little odd piles of splinters on the ground.  Do you know what these are or have any suggestions as far as removing these pests?

Answer
These are insects called borers. The insect bores into the trunk and digs tunnels in the wood and pushes out the sawdust. Spray the tree trunk with an insecticide called Onyx or Merit. Both of these will kill the borer in the trunk and also give about 3 months protection from further infestation.

usually if borers attack the tree is under stress--make sure it is watered during droughts and I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree and watered in good.