Pest Alert

The Emerald Ash Borer (EAB), a non-native insect pest that kills all species of Ash trees, has now been found in Princeton as well as in surrounding counties. This highly destructive insect has killed millions of Ash trees including many trees in our area. Princeton has formulated an EAB management plan for its approximately 1,800 Ash street trees; the plan includes tree removal and selective treatment. There is growing evidence that the White Fringetree is infested by the EAB as well.

The NJDEP State Forestry Services recommends:

  • IDENTIFY Ash trees. Ash species have opposite branches and leaves and a compound leaf with 5-11 leaflets. The bark on older trees has a unique diamond-shaped ridge bark, but younger trees may have smoother bark. Click here for images of an Ash tree and Ash tree look-alikes. 
  • MONITOR your Ash trees for the Emerald Ash Borer. You will know when the risk of mortality becomes urgent. Look for dying branches at the top of the tree, woodpecker damage, galleries under the bark, d-shaped holes, bark splits, sprouting at tree base and along trunk, and green adult beetles.
  • USE TRAPS to detect the Emerald Ash Borer in your community or woodlot. If the Emerald Ash Borer is in the area, it will be attracted to these purple prism traps.
  • SPREAD THE MESSAGE: DON'T MOVE FIREWOOD. Visitors who bring infested firewood to second homes or campgrounds near you put your trees at risk. Use only locally sourced or certified firewood.  (More information on firewood.) 

You Can Adopt an Ash Tree or Contribute to the STC Fund to Save Ash Trees

Click here for information about the Princeton Emerald Ash Borer "Adopt an Ash Tree" program and to download the participation form.(The form is also available at Princeton Public Library and at the office of the Municipal Clerk, 400 Witherspoon Street.)

Click here to download the STC Contribution Form. 



To determine the health of your Ash trees, consult Assess Ash Trees for Emerald Ash Borer.

Click here  To view the STC criteria that will help you decide whether to remove an ash tree or treat it.

Click here  To consult the Managing Emerald Ash Borer Decision Guide.  

Click here  For insecticide treatment options to protect ash trees from the Emerald Ash Borer.

Click here   For FAQs regarding potential side effects of EAB insecticides.

Click here  To view the 2016 amendment to the Princeton Trees and Shrubs ordinance that exempts ash trees from some requirements of tree removal permits. 

Click here  To watch the STC's June 23, 2016, public information session on the Emerald Ash Borer, videotaped by and courtesy of Princeton TV.

For up-to-date EAB information, consult the Emerald Ash Borer Information Network. For New Jersey, consult the NJ Department of Agriculture's EAB website.   

For more information, the following websites are helpful:


In the parking lot behind the municipal building on Monument Drive (off of Route 206 South) are two islands with four white ash trees (Fraxinus americana). The first three photos below are of the two ash trees closest to the building. Note the bark with diamond-patterned ridges and the leaflets located on opposite sides of the leaf stem. If you notice a bluish blaze at the bottom of the tree, this means the tree has been treated with an EAB insecticide (last photo).

two ashes in parking lot.