Traps set to help with the detection of emerald ash borer.
Traps set to help with the detection of emerald ash borer.

BOULDER, Colo. – If you live in Boulder County, or commute to or from points east of the City of Boulder, this spring you may notice a green or purple contraption in a tree along your main travel routes.

If so, it’s probably a trap set to help with the detection of an exotic tree-killing pest – the emerald ash borer (EAB).

To date, EAB has only been detected within the Boulder city limits, but has become a concern all over the state, as an estimated 15 percent or more of all urban and community trees here are ash.

The Colorado State Forest Service is partnering with Boulder County and the City of Boulder to place more than 120 traps targeting EAB in 2016.

Not actually intended to contain the pest population, the devices instead are being deployed to research the most effective trapping methods for the destructive pest and to try and detect its presence along roadways outside the City of Boulder.

“For the past few years, we’ve continued to try and determine if emerald ash borer is outside of the presently known infested area, by focusing on high-traffic travel corridors,” said Dan West, CSFS forest entomologist. “Early detection can be incredibly difficult if merely observing ash trees, as EAB can be present for up to four years before there are visible signs of decline.”

West says studies have shown that high-volume vehicle corridors are a pathway for the human-assisted spread of EAB through the movement of infested wood material. EAB, a non-native pest responsible for the death of tens of millions of ash trees in the United States, can fly up to a half-mile to infest new trees – but can spread much farther when people transport firewood and other raw wood.

About the Traps

Another trap used to capture adult EAB beetles.
Another trap used to capture adult EAB beetles.

The traps have a sticky surface similar to flypaper that captures adult EAB beetles, attracting them with their color and also with a chemical attractant that smells like ash leaves. The CSFS is placing the traps in tree canopies to try and determine if the pest is spreading farther than has been confirmed to date, and also to compare the effectiveness of different trapping methods.

Traps are being strategically placed near high-traffic roads on county properties and rights-of-way leading out of Boulder, including State Highway 7, State Highway 36, State Highway 119 and South Boulder Road, to seek initial detection. Other traps have been set within known infested areas of the city under various configurations, to help improve detection methods and increase future trapping success rates.

“Boulder County looks forward to continuing our partnership with the Colorado State Forest Service on EAB trapping and monitoring. Focused efforts on trapping extend the county’s efforts to detect new EAB hotspots and can help bring awareness of EAB to Boulder County residents,” said Brett Stadsvold, EAB coordinator for Boulder County.

These trapping efforts are part of a larger interagency EAB Response Team effort to help manage the spread and impacts of the pest in Colorado, and complement a national EAB survey led annually by the USDA Animal and Plant Health Inspection Service.

West says the team is hoping to have all of the traps out by mid-May; after that, the traps will be checked at least bi-weekly until past the end of the EAB flight season, when the traps will be removed in the fall.

Besides detection efforts, the CSFS also is focusing on EAB outreach. Two weeks ago, the agency released new online videos that cover ash tree identification and EAB symptoms in trees, and next week will release a revised EAB Quick Guide for Colorado.

EAB Resources

For facts and resources about EAB in Colorado, including the new videos and Quick Guide, visit our EAB page.

More information also can be found at