Emerald ash borer has made it to Douglas County. The Town of Parker says the beetle's presence in Parker was confirmed in July 2026, and the Highlands Ranch Metro District calls it the first instance documented in the county.
Per the Town, the emerald ash borer is a small, metallic green beetle that attacks and kills ash trees. If you have no idea whether the tree in your yard is an ash, same. The Town's Emerald Ash Borer in Parker page has its FAQs, and the Colorado State Forest Service has statewide guidance.
What About Highlands Ranch?
The Highlands Ranch Metro District says emerald ash borer has not been found in Highlands Ranch. Here's what it's doing anyway:
- Treating the trees that matter most. As cases got closer, its forestry team prioritized high-value, healthy ash trees for treatment, with injections or trunk sprays depending on the tree.
- Not treating everything. A significant portion of park ash trees will be treated, but the majority of ash trees on Metro District property will not be.
- 1,469 ash trees are in the District's care, about 10 percent of its tree population. How many ash trees are in private yards and commercial properties is hard to pin down.
- No new ash trees have gone in for at least 15 to 20 years. The District says tree diversity is a priority for new plantings.
More in the Metro District's emerald ash borer FAQ.
If You Think You Have an Ash Tree
Start with the Town of Parker's page if you're in Parker, the Metro District's FAQ if you're in Highlands Ranch, and a licensed tree-care company if you want someone to look at your specific tree.
Sources: Town of Parker, "Emerald Ash Borer In Parker", Highlands Ranch Metro District, "Emerald Ash Borer" FAQ and the Town of Castle Rock, which also calls the Parker detection the first confirmed case in Douglas County. Checked Sept. 27, 2026.