As Westminster heads into the hot summer season, it’s not just people and pets that suffer heat stress. Trees in Westminster and neighboring communities also suffer heat-related stress due to the high temperatures and low moisture which makes them more susceptible to tree pests. In addition to Emerald Ash Borer, an invasive tree beetle first detected in Westminster in 2019, the City’s Forestry Team has also identified the presence of Ips beetles. Both species can cause significant damage to trees, if proper precautions and/or treatment are not utilized. 

What is an Emerald Ash Borer, and how can I tell if my ash tree is infested?  

This half-inch long, dark green beetle is one of the most destructive tree pests in North America, according to the Colorado State Forest Service (CSFS). Targeting both stressed and healthy ash trees alike, the beetle bores its way into the bark and lays eggs. Larvae feed on water-conducting tissue, eventually killing the tree. The U.S. Forest Service estimates that Emerald Ash Borers are responsible for the death and decline of hundreds of millions of trees nationally since the insect was first identified in the U.S. in 2002. Emerald Ash Borers are attracted to all species of ash trees, which make up approximately 14% of Westminster’s tree canopy according to City Forester Bryan McCoy. Some neighborhoods contain an even higher percentage. All ash trees need to receive preventative treatment, or McCoy predicts they will be killed by Emerald Ash Borers within the next four years. 

According to the CSFS, damage from an Emerald Ash Borer usually starts at the top of the tree, making it hard to spot early. Determining beetle presence is often difficult to the untrained eye, but some symptoms to look for include:   

• Branches without leaves, especially at the tops of ash trees  

• Vertical splits in the bark exposing S-shaped tunnels  

• Wild leafy branches (new growth) sprouting from the trunk  

• D-shaped exit holes

What is an Ips beetle, and how can I tell if my spruce tree is infested? 

Reddish-brown to black in color, these small beetles are anywhere from 1/8 of an inch to 3/8 of an inch long. The City Forester says the presence of Ips beetles is common in Colorado, and historically, the pest appears for a few years then goes away, only to reemerge again in the future. Ips are attracted to spruce trees, and similarly to an Emerald Ash Borer, they develop under bark and bore tunnels throughout the tree that will eventually kill it. Experts say the species rarely attacks healthy trees and most problems occur when trees are under stress. The City Forester says that usually when spruce trees exhibit signs of Ips beetle infestation, it is too late to save the tree.  

According to Colorado State University, damage from Ips beetles may be limited to parts of the tree, such as a single branch or around the top. Symptoms to look for include:  

• A yellowish or reddish-brown dust accumulated in bark crevices or around the base of the tree  

• Small round holes peppering the bark of the tree  

• Woodpecker activity noted by ragged holes or patches of missing bark. (As predators of beetle, the bird’s presence may indicate bark beetle activity)  

How do I protect my trees from Emerald Ash Borers?  

1. Determine if you have an ash tree  

• Click here for our identification key to help determine if you have an ash tree in your yard. You can also use the City’s interactive tree inventory map to identify the location of different types of trees on City maintained property for comparison, by clicking here. 

2. Decide if your ash tree should be treated or removed 

• If the tree is healthy, in a good location with access to water, and has minimal prior damage, it can and should be saved. Please consult a tree care company if you need help deciding if you need to take additional steps to preserve your tree or use the CSFS Managing Emerald Ash Borer Decision guide by clicking here. If it’s determined that the tree can be saved, there are effective, environmentally-safe preventative pesticides that professional arborists can apply to protect ash trees. In a worst-case scenario, please consider hiring a qualified arborist to safely remove the tree if you determine it cannot be saved. For a list of qualified arborists in Westminster click here. 

How do I protect my trees from Ips beetles?  

1. Properly water your trees 

• This is the first line of defense in protecting against Ips beetle. Unlike an Emerald Ash Borer, Ips beetles do not usually infest healthy and properly watered trees. 

2. Determine if you have a spruce tree   

• Use the CSFS identification guide by clicking here or use the City’s interactive tree inventory map to identify the location of different types of trees on City maintained property for comparison, by clicking here. 

3. Inspect your spruce tree for damage  

• Monitor foliage at the top of the tree.  If needles appear to be missing at the top, the tree may be infected.  Also, keep an eye on neighboring spruce trees. If they show signs of Ips beetle infestation, then your tree is also at risk and should be treated.  

4. Consider removal or treatment options  

• Consult a tree care company to see if treatment or removal is warranted. It is highly recommended to hire a qualified arborist to safely remove the tree, if needed. For a list of qualified arborists in Westminster click here.  

5. Dispose of wood and tree material to protect surrounding spruce trees  

• Freshly-cut branches or logs should not be stored near healthy trees to protect against the spread of infestation  

Please note that symptoms of Ips beetle infestation are also very similar to Douglas-Fir Tussock Moth infestation. For more information and to determine whether your tree is impacted by moths, visit the CSFS website. Similarly to Ips Beetle infestation, it is best for concerned tree owners to contact an arborist to inspect trees and provide mitigation options.  

What is the City doing to protect against invasive beetle species? 

To protect against Emerald Ash Borers, Westminster’s Forestry Team has been treating City maintained, healthy ash trees on a three-year rotation since 2015. The City applies a pesticide called emamectin benzoate, which is injected directly into the base of the tree trunks. Any dead or infested trees are removed.  

To protect against Ips beetles, the forestry team first ensures that City maintained spruce trees are properly irrigated. Any infested spruce trees are removed, and nearby trees are sprayed with a preventative pesticide for protection.  

With removal of infested trees, the City focuses on replanting efforts with an emphasis on diversifying the tree canopy with drought-tolerant species.  Doing so will help protect the urban forest from the next unknown invasive pests and warming climate. 

Benefits of protecting trees:  

Protecting the City’s ash and spruce tree populations preserves the benefits they provide to existing and future Westminster residents. These benefits include increased property value, reduced stormwater runoff, reduced erosion, reduced temperature and heat island effect, sequestered CO2, improved air quality, conserved energy, and improved physical and mental health of residents while providing wildlife habitat.  

For more information on Emerald Ash Borer, Ips beetles, and resources available to Westminster residents, please visit our website at: https://www.westminsterco.gov/EmeraldAshBorer or the CSU website.