Aerial Gypsy Moth Spraying Begins in May

April 27, 2009
OPA 091/09

News Highlights  

  • Spraying will take approximately 10 days to complete, depending on the weather.
  • Maps of treatment areas can be found at public libraries, county governmental centers and online.
  • The insecticide used is a naturally occurring bacteria that isn’t harmful to people, pets or plants.

More Information 

Fairfax County will begin its annual aerial spraying program to suppress gypsy moth caterpillars starting in early May.

Helicopters will spray a naturally occurring insecticide in 20 infested areas across the county. A detailed map showing these treatment areas is available at all public library branches, county government centers and online. Treatment areas are chosen through an annual county survey of the gypsy moth population. This year the county will treat approximately 1,000 acres.

Because weather conditions are unpredictable, county officials do not know the exact days when spraying will be conducted. Once spraying begins, it may take 10 days or more to complete, depending on the weather. Typically, spraying is done in the early morning and at dusk. However, it may continue all day if weather conditions permit.

The county will use a naturally occurring bacteria — Bacillus thuringiensis or Bt. — as an insecticide. Extensive research has shown that Bt. is not harmful to people, pets, plants or beneficial insects, such as honeybees. The spray will not harm painted surfaces, and residues can be removed with soap and water.

Bt. is registered with the U.S. Environmental Protection Agency for use in forests and residential areas.  In addition, Bt. is sanctioned by the U.S. Department of Agriculture and Virginia Department of Agriculture for use against gypsy moths. 

Gypsy moth caterpillars can kill trees by defoliating them. The caterpillars feed on many different types of trees but especially like native hardwoods, such as oak. Because they have few natural predators in this country, the gypsy moth must be suppressed with insecticides. Native to Eurasia, it was accidentally released in the U.S. in the 19th century by a scientist.

More information about the treatment program, affected areas or gypsy moths, can be found online, or call the county’s Forest Pest Program at 703-324-5304, TTY 711.


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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