Fall Cankerworm on the Rise


March 27, 2012

Irene Haske
Urban Forest Management Division
703-324-5821 or 703-324-5500, TTY 711
Fax: 703-803-5955

Fall Cankerworm on the Rise in Fairfax County

Urban Foresters in the Forest Pest Management Branch noticed a significant increase in the number of fall cankerworms (Alsophilia pometaria) during their annual survey. The fall cankerworm is a native insect that destroys trees throughout North America.

In early spring, as a caterpillar, it feeds on a variety of trees. When population numbers rise, the caterpillars eat all the leaves from the trees. This may stress the trees and put them at risk, particularly in urban areas.

Due to the increased population levels of the fall cankerworm found in the Lee and Mount Vernon Districts, a spraying program is planned for mid-to-late-April in these districts only. Using ground trucks, urban foresters spray the canopy of trees with Bacillus Thuringiensis (Bt). Once the fall cankerworm ingests the Bt, they stop feeding and die within a week.

The population of fall cankerworm is monitored by urban foresters each year.

Fairfax County residents are encouraged to complete a four-question, online fall cankerworm report form at  www.fairfaxcounty.gov/dpwes/surveys/fallcankerworm.htm that will assist urban foresters to determine areas where future monitoring may take place.

For more information about the fall cankerworm, visit www.fairfaxcounty.gov/dpwes/environmental/canker4.htm.


Fairfax County is committed to nondiscrimination on the basis of disability in all county programs, services and activities. To request this information in an alternate format, or for reasonable ADA accommodations, call the Solid Waste Management Program at 703-324-5500, TTY 711.


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