10/21/2013 – Denver, CO 

We’ve been getting more information about the site in Boulder, CO where emerald ash borer (EAB) was found.  It centers around four trees within a couple of blocks, one fully dead ash tree and three others with D-shaped holes, S-shaped galleries and larval stage EAB.

The presence of dead, adult EAB is thought to  indicate a presence in the tree of two to three years.  It is almost certain that the insect was transported through firewood transport.   Branch samples will now go through a chain of inspection that we understand to be four steps before the area is added to the EAB map and a quarantine of ash wood is implemented in Boulder, CO.

The initial identification is the first step and according to this Denver Post story from October 12th, 2013 , “The protocol is determined federally and involves the state Department of Agriculture because the pest itself is federally regulated. Any infestation in a new county has to be confirmed at three agency levels: locally, meaning usually Colorado State University; then a lab in Michigan; then at the Smithsonian Institution.”

Read more: Emerald ash borer in Colorado: What homeowners can, should do now – The Denver Post

What is clear is homeowners should be identifying if they have an ash tree.  Here is a picture of the ash leafing structure on a green ash. It can vary between 5 and 11 leaflets.

green ash one leaf, 7 leaflets


EAB will not hit other tree species besides ash and it won’t hit a mountain ash which is not a true ash species.  EAB is a poor flier and Colorado doesn’t have contiguous ash tree forests making the most likely spread of the insect via firewood transport.  The green in the map below details the range of ash trees in the US.




There could be a three to five year period before EAB is able to spread beyond the discovery area and if we  control firewood transport well, up to a decade or more.  However,

“Every city is just one truckload, one bundle of firewood away, and it will always be one truckload away,” said Whitney Cranshaw, CSU Extension entomology specialist.  “If you move firewood, you’re causing other people to have very expensive problems.”

Read more on our blog:  Colorado EAB FAQ

As we talk to our clients, many think EAB is already here. This is a case of mistaken identity which leads to another complicating factor not mentioned in The Post article; the presence of the clear winged ash borer, another borer of the ash tree that is active in Denver metro.  It is a different borer then EAB.

Furthermore, amateur tree services are now running Google ads and otherwise bidding EAB prevention when it’s not warranted or crucially, it’s clear-winged ash borer that is attacking the tree.   The remedial actions to cure the tree are different.  Also it’s hard for even experts to find EAB.   Symptoms reported to be on the look out, such as thinning at the top, don’t take into account that ash trees have a hard time growing in our semi-arid climate in the first place.

“Detecting emerald ash borer itself, though, is another story, said entomologist Cranshaw. A highly effective trap eludes scientists. The thinning crown and dying limbs that are a fairly sure sign of the borer in the Midwest? ‘Here, that’s a normal-looking ash tree,’ Cranshaw said. ‘We’re a much harder place to be a tree.’