Why so many ash trees are dying right now

What the emerald ash borer actually is

The emerald ash borer is an invasive beetle from Asia, first found in North America in the early 2000s. Its larvae tunnel beneath the bark, feeding on the tissue that moves water and nutrients through the tree. Damage often goes unnoticed for years before symptoms show.

Why it kills a tree so fast

Once larvae girdle enough of a tree's inner bark, the ash can no longer move water to its canopy. Dieback usually starts at the top and works downward, and most infested ash trees die within two to four years of the first visible symptoms.

Why Southwestern Ontario got hit so hard

Ash trees were planted heavily across St. Thomas and Southwestern Ontario after Dutch elm disease wiped out the elms before them. That density let the emerald ash borer spread fast, moving tree to tree with almost nothing to slow it down.

The warning signs most homeowners miss

Thinning leaves, D-shaped exit holes in the bark, vertical bark splits, and increased woodpecker activity are all early signs of infestation. By the time a third of the canopy looks dead, the tree is usually already too far gone to save.

Why a dead ash tree turns dangerous fast

Dead ash wood turns brittle and hollow within a year or two, without the warning signs a healthy tree gives before a limb fails. That's what makes dead ash trees one of the more common causes of unexpected property damage across the region.

A dead ash tree doesn't ask for permission before it comes down. By the time it's obviously dead, it's already a hazard.

What to do if you have an ash tree

Not every ash tree needs to come down right away, but any ash showing dieback or bark splitting deserves a professional look. Trees caught early can sometimes be treated, while trees too far gone are safer removed before a storm forces the issue.

What this means for the local tree canopy

The emerald ash borer has already reshaped the tree canopy across St. Thomas, London, and Strathroy, and it isn't done. Replacing lost ash trees with more resilient species is quickly becoming part of responsible property management across the region.

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If an ash tree on your property is showing signs of decline, Out On A Limb can assess it and recommend the safest next step, whether that's treatment or removal.

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