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Westminster and EAB

Emerald Ash Borer was reported in Westminster for the first time, moving quickly from neighboring Broomfield to the north.

“In late August, EAB was found and confirmed in Broomfield in the vicinity of Zuni Street and 132nd Ave. and 128th Ave. just across the street from Westminster,” said John Kasza, city forester for Westminster. “This prompted Westminster forestry staff to do another check on August 29 of ash trees in that area of Westminster. Ash trees in the shopping center parking lot islands northeast of 128th Ave. & Zuni St. was found with the small d-shaped exit holes of EAB. We climbed up into the trees and found numerous exit holes, some with dead adult beetles in them. We peeled some bark and found the S-shaped larva galleries. We did not find any live adult beetles flying around. The fact that there were exit holes means that the adults were laying eggs on those trees last year”

Emerald ash borer in one of discovery trees in Westminster.

Source: Westminster Forestry Staff

The trees we found EAB in have been on our watch list for several years. The trees have been declining for many years, struggling with drought and other weather-related issues, and attacks from lilac ash borer. At least once or twice in previous years Westminster forestry staff along with the Colorado State Forest Service have sampled branches from these trees and placed them in rearing cages to monitor the emergence of adult beetles in the spring. The results were negative each time. This gets at some of the complexity of diagnosing EAB.

This finding is more evidence that the predicted spread of EAB into the heart of the Denver metro is slowly coming true. 

The city of Westminster has roughly 750 ash trees to be treated for EAB. Private homeowners are encouraged to treat high-profile ash trees to help protect the tree. 

Distinctive galleries from EAB trees.

Source: Westminster Forestry Staff


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