Elm trees are a defining feature of many Canberra streets and gardens, but they face a serious threat from the Elm Leaf Beetle (ELB). This small insect can cause major defoliation, leaving trees weakened, stressed, and vulnerable to long-term decline. Managing ELB effectively requires timely action and professional treatment. We recommend treating trees every three years around November.
Skeletonisation a sure sign of elm leaf beetle
Understanding Elm Leaf Beetle
- Lifecycle – Adults overwinter in sheltered places and emerge in spring. They lay eggs on the underside of elm leaves. Larvae hatch and feed on leaves from late spring through summer.
- Damage – Larvae skeletonise leaves, leaving them brown and papery. Heavy infestations can strip whole canopies.
- Spread – The beetle moves easily between trees, so untreated infestations quickly spread through neighbourhoods.
Consequences of infestation
- Loss of shade – Defoliated elms provide little cooling during hot summers.
- Stress – Trees use more energy to re-leaf, leaving them weakened.
- Decline risk – Repeated infestations can shorten tree lifespan.
- Neighbourhood impact – Untreated trees affect surrounding properties.
Treatment options
- Trunk banding – Sticky bands intercept larvae as they move down trunks.
- Soil drenches – Systemic treatments applied to soil protect new leaf growth – we don’t recommend this. It kills everything in the soil.
- Canopy sprays – Effective for heavily infested trees but require professional application.
- Pruning – Reduces hiding places and promotes healthier canopy structure.
- Trunk injection – Imidacloprid is the most effective and environmentally sound treatment for elm leaf beetle on established trees, where the insecticide is transported to the leaves to kill the beetles
Why early treatment matters
- Prevention – Stopping larvae early reduces overall population.
- Tree recovery – Early action allows leaves to photosynthesise fully through summer.
- Cost savings – Preventing infestation reduces the need for repeated treatments.
TreeWorks provides tailored elm trunk injection programs based on tree size, site conditions, and infestation levels.
🌳 Book your free inspection today and protect Canberra’s elms from Elm Leaf Beetle damage.