Washington Forest Health Issues in 2003

Western Hemlock Looper

The western hemlock looper is a native defoliator of hemlock and interspersed conifers.

The outbreak north and east of Mt. Baker has mostly subsided! Only 1,411 acres were mapped in 2003, down from approximately 35,215 in 2002 and 17,000 acres in 2001.

Over 7,500 acres of scattered hemlock mortality were mapped where hemlock looper defoliation has occurred in recent years.

Bark beetles and root diseases combined with the direct effects of defoliation likely contributed to tree death.

No current hemlock looper or phantom hemlock looper damage was observed in the vicinity of Granite Falls this year. This defoliation event appears to have collapsed. Since hemlock looper is primarily a defoliator of older forests with a complex multi-layered structure of western hemlock, this area of second growth hemlock, uniformly 55-60 years of age, with little understory was unlikely to sustain a prolonged outbreak.

Additional Information

Historical Activity with Drought Correlation