Emerald Ash Borer

The Emerald Ash Borer (EAB) is an invasive beetle first identified in the United States in 2002. In 2013, it was identified in Boulder, and it has recently been found in three other nearby Colorado communities. EAB is a federally quarantined, invasive tree pest responsible for the death or decline of more than 50 million ash trees to date.

The City of Greeley first developed its management plan in 2014, and as of late 2017, the beetle had not been found within city limits. 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 can 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 can 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 the EAB

About the Emerald Ash Borer (EAB)

Emerald ash borer (EAB), Agrilus planipennis fairmaire, is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. 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.


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.


Signs of Infestation

By the time leaves show evidence of EAB, significant damage has been done to the tree’s interior, which is why early detection of the beetle’s presence is important.

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 970-339-2405.

Managing the Emerald Ash Borer

If the EAB is detected in the City of Greeley, to prevent the further spread in Colorado, the Colorado Department of Agriculture will impose and enforce a quarantine on the movement of ash tree products (i.e., chipped wood, branches, logs, stumps and firewood). If that happens, a landfill will be identified for public disposal of EAB-infested material. The City of Greeley Forestry Program maintains an inventory of publicly owned trees, and that includes all varieties of ash trees. City staff will immediately begin determining the health of each infected tree located on city property and treat or replace it, depending on its health.

Private properties with an infected ash tree larger than 15 inches in diameter and in good health can hire a professional to treat it with insecticide, or they can choose to remove the tree and dispose of it in the pre-determined ash tree drop-off site. If the tree is smaller than 15 inches in diameter, residents can choose to treat otherwise healthy trees themselves. If the tree is in poor health, it may need to be cut down and taken to the disposal site. Keep in mind that it could take up to three years for a tree infested with the insect to show signs of decline, so regular inspections are recommended.

Contact Us


2631 52nd Avenue Ct
Greeley, Colorado 80634

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

970-339-2405 tel
970-339-2452 fax

Helpful Links

General EAB information: EmeraldAshBorer.info

EAB in Colorado: (survey progress, identification, reporting, quarantine boundaries and treatment options): EabColorado.com

Facts about insects and diseases that threaten Colorado’s trees: CSFS.Colostate.edu