"It's the elimination of a genus from this part of the continent, which is absolutely staggering," said Richard Ubbens, the city's director of urban forestry. "It will wipe out all ash trees."

The emerald ash borer beetle, a shimmering blue-green insect native to parts of east and central Asia, has been eroding the ash population of the northeastern United States and southwestern Ontario for years. Larvae eat serpentine pathways just beneath the bark, which slowly cut off the flow of water and nutrients within the tree; death may take years.

Attempts to slow the beetle's onslaught have thus far failed: carving out and cutting down vast swaths of ash in southwestern Ontario, in a tactic similar to those used to slow forest fires, did not halt the spread of the beetle eastward. A pesticide derived from the neem tree, called TreeAzin, costs roughly $300 per tree to apply, making it impractical for all but the largest, most beloved of privately owned ash trees, Ubbens said. TreeAzin will only act like a "vitamin" would against a cold – meaning it is no guarantee.

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