Insects that bore into trees
Insects that drink sap and eat plant parts typically attack the leaves or fleshy portion of the tree, which generally does not kill the plant. Boring insects, on the other hand, bore into the main truck or side branches, causing much more serious damage such as branch dieback, structural weakness or decline and death of the plant.
Some insects will bore into healthy trees, but in many cases, the borers are attracted to weak ones. Insects that only bore into weakened trees are known as “secondary attackers,” because they strike trees that have been weakened by another stress. When borers attack trees, they normally leave behind telltale signs such as holes in the tree, patches of resin, gummy substances exuding from the bark, sawdust or waste products, commonly known as “frass.”