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Emerald Ash Borer

Emerald Ash Borer (EAB), Agrilus planipennis Fairmaire, is an exotic beetle discovered in southeastern Michigan near Detroit in the summer of 2002. In 2013, it was identified in Boulder, and it was recently found near the Town of Berthoud in Larimer County. The borers are metallic green and up to one half inch long; adult beetles nibble on ash foliage but cause little damage to the leaves themselves. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients. Infested trees gradually die over a period of approximately two to four years.

The City of Greeley first developed its EAB management plan in 2014. By educating the public on how to identify and avoid bringing the beetle to the area (and to manage the beetle when it is found inside city limits), we help protect the city’s urban forest from the potential dangers caused by the pest.

At this time, the Emerald Ash Borer has not been identified in the City of Greeley. The City of Greeley Forestry Program pro-actively collects samples from local ash trees on a regular basis to look for the beetle’s presence. By educating our community, we also encourage residents to keep watch for the beetle’s presence.

With EAB, it is not a matter of if the beetle will appear in Greeley; it is a matter of when.

What Can You Do?

  • Do not move firewood! If you go camping, burn or dispose of the wood where you buy it
  • Determine if you have an Ash Tree
  • If planting new trees, plant other tree varieties not impacted by EAB

Ash Tree Identification

Only ash trees are at risk from the EAB. In Greeley, ash trees make up around 15% of the urban forest. Homeowners may not even realize they have an ash on their property.

Here are some characteristics:

  • Multiple leaves come from a single stalk and typically have five to eleven leaflets
  • Leaflet margins are smooth or finely toothed along the edge
  • When present, seeds are paddle-shaped
  • Branches and buds grow directly opposite each other
  • Mature bark displays diamond-shaped ridges

Please note: European Mountain ash trees, Sorbus aucuparia, are not true ash and are not susceptible to EAB.

Photo courtesy flickr user Virens (Latin for greening) under creative commons license


Signs of Infestation

By the time leaves show evidence of EAB, significant damage has already been done to the tree’s interior. Early detection of the beetle’s presence is important to keeping Greeley's urban forest healthy.

Signs of an EAB infestation include:

  • Sparse leaves or branches toward the top of the tree
  • Increased woodpecker activity
  • D-shaped exit holes approximately 1/8 inch wide
  • Vertical splits in the bark

If an ash tree appears unhealthy, consider having it examined by a professional. If you suspect your tree has been infested by the EAB, call the City’s Forestry Program at 970-351-5150.

Contact Us


2631 52nd Avenue Ct
Greeley, Colorado 80634

Monday - Friday
7:00 a.m. to 3:30 p.m. 

970-351-5150 tel

Helpful Links

General EAB information:

Facts about insects and diseases that threaten Colorado’s trees:

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