Ask Extension Database, NDSU Extension Service Ask Extension for answers to commonly asked questions. Almost all woody plants are subject to attack by insects that tunnel or bore into the stem, branches and shoots. Most borer problems occur in plants under stress. This stress may be a poor planting site, drought injury, construction damage or lawn mower wounds.
Healthy trees attract fewer insects and can withstand some borer activity.
The healthy tree can also flush out borers with a heavy sap flow. The first indication of borer attack is usually some dieback or thinning of the tree. If you see the sawdust or holes in the side of the tree, this is also an indication that insects have invaded the woody portions of the plant. You can control some borer problems by pruning out the infested plant parts. Before you can begin any chemical treatment you should know what type of insect is involved.