Tree Borers

Recognize the signs

Evidence

Fresh boring dust, sap, galleries, larvae or emergence holes support a borer investigation. Holes can persist after insects leave.

Context

Host species, height of damage, crown condition and recent drought or injury help narrow the cause. Hole shape alone is insufficient for species identification.

Differences that change the decision

A similar-looking organism can need a different response. Compare the evidence and what it changes.

Compare every column. On a narrow screen, scroll the table sideways.

What else could it be?

Woodpecker or sapsucker activity

Bird-made holes or bark removal may be primary activity or a response to insects. Observe the bird and pattern.

Compare birds ↗

Canker, root disease or drought

Sap and crown decline are not exclusive to insects.

Compare plant disease & stress ↗

Structural wood pests

Insects in furniture or buildings require a different inspection and moisture assessment.

Compare wood boring beetles ↗

Inspect the right places

1. Record without damaging the tree

   Photograph the whole crown, trunk injury and fresh dust with a size reference. Identify the tree; do not peel healthy bark or make exploratory wounds.

2. Assess safety and movement

   Keep people away from failing limbs. Leave suspect wood at the site pending local disposal or quarantine advice.

Choose a proportionate response

For pesticides, the local product label determines the allowed pest, site, precautions and timing. Check safety and regional guidance.

1. Correct avoidable stress

   Check irrigation, root-zone compaction, trunk ties and mechanical injuries. Care must match the tree and site; repeated shallow lawn watering may not meet tree needs.

2. Obtain a severity assessment

   An arborist can distinguish localised branch attack from extensive trunk damage and advise pruning, preservation or removal. Damaged limbs require safe professional work.

3. Protect neighbouring trees when justified

   Any preventive treatment needs the identified pest, local emergence timing, tree condition and authorised product/application method. Some invasive borers warrant specialist treatment of trees that remain viable.

Avoid these mistakes

• Do not promise to save a heavily infested or structurally failing tree with a surface spray.
• Do not probe trunks indiscriminately or pour pesticide into holes.
• Do not move firewood or infested nursery stock to another location.

Check whether it is working

Prevent a return

• Choose site-adapted trees, protect roots and bark and maintain appropriate water supply.
• Buy firewood where it will be burned and obey current movement restrictions.

Common questions