Insects that tunnel through the stems and trunks of trees and shrubs can be very destructive pests. Most wood-borers are the larvae (immature stages) of certain moths and beetles. They can feed on all woody parts of the tree, including growing points, stems, main trunks and sometimes even roots.
They use their well-developed, chewing mouthparts to tunnel or remove woody tissue, which can provide an entry point for plant pathogens. While dieback of the damaged area is the most common symptom, different insect groups often have slightly different symptoms including the way they tunnel, deposit their frass (insect waste and chewed wood articles), and whether they produce webbing or stain on the tree.
Once boring insects are present, they can be very hard to remove while still producing a saleable plant; prevention is critical. Some of the most important boring beetle groups include longicorn beetles, weevils, jewel beetles, bark beetles, ambrosia beetles and pinhole beetles. Some important boring moths include fruit tree borer moth, wood moths and clearwing moths.
For more information on the management of wood-boring insects refer to the factsheet. Additionally, more specific information on certain wood-boring insects can be found on the Pest ID tool including polyphagous shot hole borer, macadamia nutborer and various others.
Figure Caption: Callistemon tip borer damage.