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The Emerald Ash Borer (EAB):

  • Is an insect that has the potential to destroy Metro Denver’s 1.45 million ash trees. It has already wreaked havoc in more than 30 states and parts of Canada, causing billions of dollars in damage.
  • Arrived in Boulder in 2013, Broomfield in 2019 and Arvada in 2020. It’s only a matter of time before it arrives in Denver, if it hasn’t already. Unfortunately, it takes two to four years for signs of EAB infestation to manifest.
  • Has a limited flight range. It most commonly travels with humans who are transferring untreated ash tree firewood, chips larger than one inch, or nursery stock.
  • Eggs hatch and become worm-like larvae that tunnel through the tree’s water-conducting tissue just under the bark. The tunneling and feeding under the bark is what eventually kills the impacted tree.
  • Feasts on ash trees only, including the green (Fraxinus pennsylvanica) and white (Fraxinus americana) varieties, which are the most common in Denver.

Identifying EAB

The EAB is small enough to fit on a penny. The adult EAB is identifiable by its dark, metallic-green color and coppery-red or purple abdomen, which can be seen under its wings. 

EAB Infestation

How can you tell if your ash is infested by the EAB? Start by looking for these tell-tale signs:

EAB Devastation

If seeing is believing, take a stroll through the once-thick forests in the 36 states and parts of Canada where millions of ash trees now rot. Property owners and forest product industry operators have lost billions of dollars to the EAB.

Images courtesy Colorado State Forest Service