Blog module icon

Invasive Species Management

Jun 26

[ARCHIVED] Emerald Ash Borer

The original item was published from June 26, 2020 11:23 AM to August 4, 2021 5:09 PM

EAB Tips for Front Range Residents

EAB was recently found in Arvada.  Jefferson County CSU Extension and Jeffco Invasive Species Management want homeowners to understand what they can do to prepare for Emerald Ash Borer (EAB), a non-native insect that attacks and kills ash trees. 

What You Can Do

Determine now if you have any ash trees. Identifying features of ash trees include compound leaves with 5 to 9 leaflets; leaflets, buds and branches growing directly opposite from one another; and diamond-shaped bark ridges on mature trees. More information about identifying ash trees can be found at the Colorado State Forest Service Emerald Ash Borer website.

If you have an ash tree, start planning. Decide if the overall health of the tree merits current or future treatment or if it would be best to remove and replace it with a different species. If you aren’t sure, contact a certified arborist. If pesticide treatment is the preferred option, the applicator must be licensed by the Colorado Department of Agriculture as a Commercial Pesticide Applicator.  A good resource for treatment options is Insecticide Options for Protecting Ash Trees from Emerald Ash Borer

Recognize signs of EAB infestation. Property owners with ash trees should be on the lookout for thinning of leaves in the upper tree canopy, 1/8-inch D-shaped holes on the bark and vertical bark splitting with winding S-shaped tunnels underneath. Report suspect trees by calling the Colorado Department of Agriculture at 1-888-248-5535 or filling out their EAB Report Form.

Be aware of EAB imposters. Other insects like lilac/ash borer, ash bark beetle and flat-headed apple tree borer may look like EAB or cause similar tree symptoms.

Help prevent spread of EAB.
Do not transport ash or any hardwood firewood, or any other ash wood products, to other locations. Firewood and wood products can harbor insect and disease pests.

For more information about ash tree identification, Emerald Ash Borer symptoms and control visit the CSU Extension  and Jeffco Invasive Species Management pages.


Arvada EAB 

Boulder EAB

Broomfield EAB

Lakewood EAB

Westminster EAB

Colorado Department of Agriculture

Colorado State Forest Service