Homeowners Should Treat Emerald Ash Borer Now

April 22, 2010
OPA 083/10

News Highlights  

  • Protect ash trees May through June from the emerald ash borer.
  • Non-toxic glue traps will be hung in trees across the county to monitor the spread of this insect that kills ash trees.
  • Don't transport firewood because it helps to spread this pest; quarantines ban transporting firewood outside certain Northern Virginia localities or across state lines.

More Information

epicormic shoots
Epicormic Shoots

bark splitting
Bark Splitting

map of Fairfax trapping area
Fairfax Trapping Area

Emerald Ash Borer and Firewood Quarantine video
Emerald Ash Borer and Firewood Quarantine Video video icon

Homeowners who wish to protect their ash trees from the emerald ash borer should take action in May through June, say county officials. Every ash tree is at risk from this insect because it has been found across the county.

Many healthy or infested ash trees can be treated with an insecticide available at many garden stores. Look for any insecticide that contains the chemical imidacloprid.

For trees with trunks greater than 15 inches in diameter, homeowners should seek treatment from a professional tree care firm. They can inject the chemicals directly into a tree's trunk which will last longer than other treatments available to the public.

If a tree has lost more than 50 percent of its leaves, insecticides most likely won’t work, and there are no other treatment options.

Insecticides are most effectively applied in May through June because trees are more likely to absorb the chemicals as they revive in spring. It takes four to six weeks for the insecticide to be thoroughly distributed within the tree. Insecticides available to homeowners must be reapplied once a year, and professional treatments need to be repeated once every one to three years, depending on the insecticide used.

Two signs indicate that an ash tree may be infested with the emerald ash borer:

  1. Trees may have horizontal splits or fissures in their bark
  2. Trees may have small shoots or branches growing from the trunk, called epicormic shoots.

To track the insect’s spread, glue traps will be hung in ash trees across the county starting April 26. Approximately 500 traps will be placed across the county as part of a statewide effort to track the insect. 

The large, purple, triangular traps are non-toxic. They don’t contain pesticides or chemicals. To catch the insects, however, the traps are baited with natural plant oils and covered with non-toxic glue.

Officials ask the public to report traps that have fallen to the ground, and advise not to touch them since they are covered with extremely sticky glue. To report fallen traps, call the Fairfax County Forest Pest Branch at 703-324-5304, TTY 711.

To prevent the spread of this insect, state and federal quarantines ban the transport of firewood. The quarantine covers Fairfax, Arlington, Fauquier, Loudoun and Prince William counties and the cities of Alexandria, Fairfax City, Falls Church, Manassas and Manassas Park.

Firewood may not be taken outside these areas or across state lines. However, firewood may be transported within the quarantined areas. When camping outside the quarantined areas, use firewood from local sources, instead of transporting it. Violating the quarantines can result in fines of up to $250,000.

The emerald ash borer was discovered in Fairfax County in 2008. These insects have killed more than 25 million ash trees in the U.S. The borers are native to China, Korea and Japan, and they first arrived in this country from Asia in the 1990s.

For more information about the emerald ash borer, effective treatments or the trapping program, contact the Fairfax County Forest Pest Branch at 703-324-5304, TTY 711 or by e-mail.


Get News. Get Information. Get Fairfax County.Contact: Merni Fitzgerald, Director, Office of Public Affairs
703-324-3189, TTY 711, Media Pager: 703-324-NEWS (6397)
To request this information in an alternate format, call 703-324-3187, TTY 711

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