06-05-2025
DCNR aerial spraying targets fall cankerworm in Somerset County
(WTAJ) — Aerial spraying is set to begin in parts of Somerset County to stop an outbreak of fall cankerworms, a native but destructive pest threatening already stressed forests in western Pennsylvania.
The treatment, led by the state's Department of Conservation and Natural Resources (DCNR), will take place around the same time as the larger, statewide aerial spray campaign to suppress spongy moth populations across 13 counties.
While much of the focus remains on the spongy moth, DCNR will also treat forest areas in Somerset, Fayette and Westmoreland counties for the fall cankerworm (FCW), an inchworm-like caterpillar that feeds on the leaves of hardwood trees. The repeated defoliation by FCWs, especially when combined with recent drought and pest pressures, has weakened many trees in these regions.
Fall cankerworms typically emerge in late fall and early spring. The caterpillars feed heavily on leaves, particularly from oak, elm and maple trees, stripping them of their foliage and weakening the trees over time. Repeated infestations can severely stress forests and delay recovery from other environmental impacts.
The DCNR's ariel suppression campaign for spongy moths defoliated nearly 600,000 acres in 2024. Officials say the decline in acreage to be treated this year, just under 75,000 acres, shows progress, though hotspots remain.
The spongy moth spraying will cover 65 sites across 5 state forests and 7 state parks, including areas in Lycoming, Dauphin, Pike, and Clinton counties. The Pennsylvania Game Commission will treat another 38,000 acres on State Game Lands.
Both suppression efforts will use targeted insecticides safe for other wildlife and will be applied by helicopters and fixed-wing aircraft. Spray zones for the FCW treatment in Somerset County and spongy moth suppression elsewhere can be viewed on DCNR's interactive map.
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For more information about forest health and aerial spray programs, visit DCNR's website.
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