Forest Pest Insects and Disease

DCNR protects Pennsylvania's forests, both public and private, from harmful insects, diseases, and other destructive agents. The Bureau of Forestry promotes programs  to improve and maintain the long-term health and biodiversity of forest ecosystems, including urban forests. The bureau evaluates factors affecting the health of trees and woodlands, utilizes integrated pest management techniques to mitigate the effects of destructive agents, and promotes forest health to the public.



Check this page for current alerts about pests of Pennsylvania trees.


What is Killing My Tree?

Explore resources and find help dealing with pests and diseases of landscape trees.



Asian Longhorned Beetle

Watch out for this voracious pest that invades new sites riding in wooden pallets, crates and firewood.


Emerald Ash Borer

This metallic green beetle has destroyed millions of ash trees since its arrival from Asia.



Thousand Canker Disease

This disease complex poses a significant new threat to Pennsylvania's black walnut.


Gypsy Moth

First discovered in Pennsylvania in 1932, the gypsy moth is responsible for damage to millions of trees especially oaks.



Hemlock Woolly Adelgid

This sap-sucking relative of aphids is a serious pest of our state tree in forests and ornamental plantings.


Forest Tent Caterpillar

This pest defoliated more acres of woodlands in 2010 than all other caterpillars combined. Download the U.S. Forest Service Pest Alert for Forest Tent Caterpillar.


Fabrella fungus magnified

Tree Diseases

Learn more about the blights, cankers, root rots and leaf spots that attack our trees in yards, parks and woodlands.


Forest Health Fact Sheets

Visit our library of PDF brochures and factsheets describing a variety of forest pests and diseases.