Friends Oppose County Spray Program

On November 18, 2014, the Friends voted unanimously to adopt a Resolution Opposing Fairfax County Fall Cankerworm Spraying Program. Since then, we have continued to research the issues involved in spraying, many of which are summarized in a letter to former Supervisor Hyland.

In 2014, Fairfax County sprayed about 2,000 acres from helicopters to suppress Fall Cankerworms, a native insect (a moth) that can defoliate trees in its larval state. Most of the sprayed areas were in the Mount Vernon District. Two areas sprayed were on Little Hunting Creek: 170 acres in Wessynton and Riverside Estates communities, and another 92 acres within a few blocks of the creek, across Route 1 southwest of Janna Lee Avenue.

The County uses the insecticide Bacillus thuringiensis var. kurstaki (Btk), a naturally occurring soil bacterium that is believed to be safe for humans and other mammals.

Why are we opposed?

Btk kills all moth and butterfly (Lepidoptera) caterpillars that ingest it, including Tiger Swallowtails, Virginia's state insect.

Fall Cankerworm (unlike Gypsy Moth) is native insect, and many species of wildlife depend on it as a food source, especially migrating and nesting birds. Btk spraying deprives birds of a major food source at the height of migration and nesting season.

Fall Cankerworm populations are controlled by natural predators (in particular, a parasitoid wasp). Btk also suppresses these species, and thus may delay or disrupt the natural population controls for Fall Cankerworm outbreaks.

Concern about direct and indirect effects on non-target species (birds, butterflies) have led other organizations also to oppose the County's spray program, including: