Emerald Ash Borer

Emerald Ash Borer has been confirmed to be present in West St. Louis County.  Emerald Ash Borer (EAB) is an exotic beetle that was discovered in southeastern Michigan during the summer of 2002.  Since its discovery, EAB has spread quickly and, in a matter of eight years, has established itself throughout Michigan, as well as in Illinois, Indiana, Iowa, Kentucky, Maryland, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, Wisconsin, West Virginia, and Ontario, Canada.  The beetle kills trees by damaging the sapwood and interrupting the tree’s ability to transport fluids.  Ash trees infested with EAB typically die within five years.

For information about Emerald Ash Borer, including identification, symptoms of infestation, life cycle, location of infestations throughout the US, and ash tree identification, visit

The City has long been aware that there is a high population of Ash trees in the public right of way (typically the area between the sidewalk and street.)  Since 2010, City staff has been diligently working to reduce the population of Ash street trees in preparation for an EAB infestation by removing dead and declining trees.  We have made great headway and have reduced the population of Ash trees from 36% of our total street trees to 28%.  However, there remains approximately 6,700 Ash trees on City streets.  We expect to see a dramatic increase in the mortality of Ash trees for the next 3-5 years. 

Ash trees killed by EAB quickly become brittle and fall apart, creating potential hazards to public safety.  The estimated cost to contractually remove these trees is in excess of 3.5 million dollars.  However, the Department of Public Services has developed an alternative strategy to utilize in-house maintenance personnel to remove City maintained Ash trees throughout the City within a seven-year period.  This plan minimizes costs and maximizes efficiency by re-allocating existing staff and eliminating an over reliance on contractors who will be in high demand during the Ash crisis.

Ash tree removals will be prioritized and scheduled based on condition, size, and threat.  While the ultimate result is complete removal of the City-owned Ash trees, it is undesirable and ineffective to simply start at one end of the City and globally remove all Ash trees in each neighborhood.  Accordingly, the City will be strategically scheduling the removals in order to lessen the immediate impacts in individual neighborhoods so that the drastic impact of removing 6,700 trees will be distributed throughout a seven year period. 

If a tree in front of your home has been scheduled for removal, you will be notified by mail before the removal takes place. If you have a declining Ash tree in City right-of-way adjacent to your home that you would like to be considered for removal, please call us at 636-537-4000, or fill out a work request here.

The scope and impacts of the EAB infestation will be immense, and the removal of these trees will have a dramatic visual impact within many of our neighborhoods.  The Residential Street Tree Program is available to assist residents who wish to replant trees that have been removed due to Emerald Ash Borer.  The program policy and participation materials can be found here.

There are chemical treatments available to temporarily fend off EAB damage to trees.  This treatment typically provides protection from EAB for up to two years, and must be re-applied biennially.  While such treatments may be desirable for private owners of Ash trees, it is not a realistic option (financially or logistically) for City-maintained street trees.  Estimating an application cost of $200 per City-maintained tree would result in an annual expenditure of $650,000 in perpetuity.  Further, there is no guarantee the treatment will be successful, as the stress caused by the treatment will likely kill the tree over time.

In an effort to assist and support Chesterfield residents who may choose to treat their private Ash trees, the Department of Public Services has created a list of vendors who have met City qualifications and insurance standards, available here.

Additionally, in order to assist and support Chesterfield residents who have a dead or dying Ash tree on private property that requires removal, the Department of Public Services has created a list of available tree removal services who have met City qualifications and insurance standards, available here

If you would like to replant trees on private property, a list of available planting services who have met City qualifications and insurance standards is available here.

If you are a professional tree service and are qualified to perform removals, planting, or preventative treatment, and you would like to be on the City’s list of available vendors, please submit proof of insurance, verification that ISA Certified Arborists are on staff for removals, and verification of chemical applicator’s license if you perform preventative treatments.