Printer
TextFall Cankerworm
The fall
cankerworm, Alsophila pometaria, is a native defoliating insect
found throughout much of North America. The caterpillar stage of these
insects is often referred to as inchworms or loopers. Fall cankerworms
feed on a wide variety of trees but tend to prefer maples, hickories,
ashes, and oaks, all of which are found in abundance throughout Fairfax
County. Fall cankerworm caterpillars emerge in early spring and feed on
leaves for about a month. Once the caterpillars mature, they drop off the
trees, enter the soil, and pupate. You can look for the wingless females
and their egg masses on the trunks of trees in January and February.
Infestations in Fairfax County
Severe infestations of cankerworms can cause widespread defoliation, tree stress and possible tree death. Major infestations and defoliation have occurred in Fairfax County:
- 1996 and 1997, along the George Washington Parkway near Mount Vernon
- 1998, nearly 1500 acres of defoliation throughout the Lee and Mount Vernon Districts
- 1999, nearly 5000 acres of defoliation in southeastern Fairfax County
- 2002, approximately 2000 acres of defoliation in the Mason Neck area of the county
Since 2002, no significant defoliation has been detected in the county. County foresters will continue to monitor fall cankerworm populations and develop suppression programs as warranted.
Fall cankerworm female moth laying eggs
For further information, or if you find signs of this insect on your property, contact the Fairfax County Forest Pest Branch at 703-324-5304, TTY 711, or via e-mail.
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