Webworms erupt in the Allegheny

This fall 2011 webworm outbreak in the Hickory Creek Wilderness Area of the Allegheny National Forest, Pennsylvania stands out against the near normal (blue) background that dominated the state in early fall. There were minimal indications of defoliation in mid-August, but clear patterns of severity were clear by mid-September. This anomaly persisted through November, when leaflessness is the normal pre-winter condition for deciduous trees. Recognizing insect defoliations near the end of the growing season is especially challenging as decline in greenness is rapid and it varies from year to year with temperature.