Home & Woodlot Owners

MONITORING & DETECTION

Detection:

It is difficult to detect Emerald Ash Borer in newly infested trees because they exhibit few, if any, external symptoms. Vertical cracks in the bark over larval feeding galleries is the first sign of infestation. This is soon followed by flaked bark and jagged holes excavated by woodpeckers feeding on larvae. D-shaped exit holes left by emerging adult beetles may be seen on branches or the trunk, but these can be difficult to see where the bark is rough. When the bark is removed from infested trees, the larval galleries that etch the outer sapwood and phloem are readily visible.

As Emerald Ash Borer densities build, the tree canopy becomes increasingly thin, and branches die off. Many trees lose 30-50 percent of the canopy after only a few years of infestation. Trees may die after only 2 to 3 years of heavy infestation. Epicormic shoots may arise on the trunk or branches of the tree. Dense stump sprouting sometimes occurs after trees die.

Emerald Ash Borer larvae have developed in branches and trunks ranging from 2.5 cm (1 inch) to 140 cm (55 inches) in diameter. Although stressed trees are initially more attractive to egg laying adults than healthy trees are, given time all ash trees greater than 3 cm in diameter will be attacked.

See EAB Signs and Symptoms and EAB ID for more details on what to look for.

 

Monitoring:

Purple Prism Traps

Purple Prism Traps (PPT's) are for detection or monitoring purposes only. They are placed in areas where EAB has not been found to determine if it is present. They are not used to control EAB populations. Emerald Ash Borers are attracted to the purple color of the traps, which are covered in a sticky substance you don't want to touch. The traps are also baited with a lure made of oils that are similar to those present in ash trees. PPT's cannot be purchased; they are part of the United States Department of Agriculture surveying program. Read more about the Purple Prism Traps at the Management and Control Page.

 

Purple Prism Monitoring Trap in an Ash Tree
Photo Credit: Rebecca Hargrave, Cornell Cooperative Extension

In addition, to Purple Prism Traps, the Emerald Ash Borer can be monitored using what is termed "bio-surveillance". This is simply watching the foraging activities of a native, stingless predatory wasp. For more information, see Management and Control or visit http://www.cerceris.info.

 


Trap Trees

 

Girdling ash tree
Photo credit: Mark Whitmore, Cornell University

Since, Emerald Ash Borers are attracted to the chemicals stressed ash trees release, girdled trees can be used as trap trees. A tree is girdled by removing the outer and inner bark in a ring completely around the trunk. This trapping technique is expensive because girdled trees are removed at the end of the season and the bark is carefully peeled to determine if there is EAB present. EAB is often found in trap trees when it was not caught on traps placed in the trees.

 


 

Peeling ash logs for signs of EAB
Photo credit: Mark Whitmore, Cornell University.

You don't need to have a PPT to have a trap tree on your property. All you need to do is girdle a tree, wrap plastic food wrap above the girdling wound, then paint the plastic wrap with sticky bug trapping goop that can be obtained at your local garden supply store.

 


At the end of the year, properly fell the tree and peel the bark off layer by layer using a draw knife. Inspect each layer for signs of EAB. This is a detailed and delicate procedure. Contact your local Cornell Cooperative Extension or DEC office for more information.

Monitoring Your Trees

The NYS DEC has EAB Monitoring and Reporting Protocol. The protocol walks through an inspection process and provides forms for you to keep track of your trees. Check the NYS DEC's site for more information: http://www.dec.ny.gov/animals/72136.html

USDA APHIS also has a monitoring and reporting program designed for groups to periodically check ash trees for EAB. This system is great for groups, clubs and families that want to report on multiple trees and keep track of them over time. Check out http://beetledetectives.com/.

 

Additional Resources