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Emerald Ash Borer Confirmed in Larimer County

Fall, 2019

Emerald ash borer (EAB), is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients, eventually causing the tree to die. Emerald ash borer has now been confirmed in Larimer County.

Signs and Symptoms- The leafy canopy of infested ash trees will begin to look thin. EAB chews through the tree’s water and nutrient-conducting tissues, strangling the tree. If there is a high population of EAB in the tree, the leafy canopy in ash trees will start to die. A third to a half of the branches may die in one year. Most of the canopy will be dead within 2 years of when symptoms are first seen. Sometimes ash trees push out sprouts from the trunk after the upper portions of the tree dies. The adult beetles will leave a “D”-shaped hole in the bark, roughly 1/8 inch in diameter, when they emerge in June.

Since its discovery, EAB has:

Killed hundreds of millions of ash trees in North America.Caused regulatory agencies and the USDA to enforce quarantines and fines to prevent potentially infested ash trees, logs or hardwood firewood from moving out of areas where EAB occurs.Cost municipalities, property owners, nursery operators and forest products industries hundreds of millions of dollars. For more information, please visit or visit our and schedule an Arborist to come look at your Ash trees. Please contact us as soon as possible to approve your preventative EAB treatments for Spring 2020.

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