EAB was first found in our area on the University of Colorado Boulder campus in September 2013. Since then, EAB has been found in many Front Range communities, including: Erie, Broomfield and Thornton as well as Adams and Larimer counties. State officials confirmed EAB in Louisville in May 2020.
Parks Division
Invasive beetle management
Invasive species
Agrilus planipennis
Emerald Ash Borer
The Emerald Ash Borer, or EAB, is a beetle that attacks ash trees. It is a serious threat to all ash tree species in North America.
Once EAB is in an area, it can quickly kill ash trees that are not protected.
Emerald Ash Borer in Colorado and Louisville
How the City manages Emerald Ash Borer
Louisville has about 123,000 trees. About 18,000 are ash trees. About 1,000 ash trees are on public property, and about 20% of those are considered high-value trees. High-value trees are large, healthy, well-formed, and often located in parks or other important public areas.
As a short-term management approach, City staff have recommended treating high-value ash trees with insecticide trunk injections. The City uses an organic-labeled product with the active ingredient azadirachtin. Treatment costs can vary based on trunk size, number of treatments needed, and whether the work is done by City staff or an outside contractor.
Long-term tree canopy management
For long-term care of Louisville’s tree canopy, staff recommend planting a wider mix of tree species. A more diverse tree canopy is stronger and better able to handle pests, disease, drought, and other future threats.
Ongoing City efforts include:
- Discouraging the planting of new ash trees
- Removing ash trees when needed, whether they are infected or not
- Requiring or encouraging a wider variety of tree species in new public and private development projects
Emerald Ash Borer information and resources
Recommended Insecticides: Non-neonicotinoid insecticides, such as azadirachtin, emamectin benzoate, acephate, and bifenthrin.
Helpful resources may include:
- Questions and Answers >
- November 2013 Announcement >
- EAB detected in Louisville, 2020 >
Please see this website from the Colorado State Forest Service for more information and resources.
Ips hunteri
IPS Bark (Engraver) Beetle
The IPS beetle is a tree pest found along the Front Range. It can attack Colorado blue spruce, which is Colorado’s state tree.
There are 11 species of IPS beetles in Colorado. Louisville residents should be most aware of Ips hunteri. This species is attacking Colorado blue spruce trees along the Front Range.
IPS beetle activity in Colorado and Louisville
The City of Fort Collins has removed several blue spruce trees because of Ips hunteri infestations. Other nearby cities have also seen similar problems. Louisville has not had the same level of outbreak. However, a few trees have been attacked. The City Forester will continue to monitor City spruce trees and take steps to help prevent an outbreak.
Tree care professionals have found Ips hunteri on large, mature Colorado blue spruce trees in urban landscapes. Many of these trees were stressed by drought.
How to help prevent IPS beetle attacks
The best way to prevent IPS beetle attacks is to keep trees healthy. IPS beetles usually attack stressed trees. They rarely attack healthy trees.
Trees are more likely to be attacked if they are:
- Newly planted or recently transplanted
- Stressed by drought
- Not getting enough water
Residents should keep trees on a regular watering schedule. It is important to maintain soil moisture throughout the year, including during dry periods.
More information about Ips hunteri is available from Colorado State University.
Request help or a consultation
For more information about tree care or to request a consultation, contact:
Chris Lichty, City Forester
Phone: 303-335-4733
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