Western hemlock looper

This insect periodically reaches outbreak levels, causing severe damage to forests in both Interior and coastal stands in British Columbia.

On this page

• Description
• Host tree species
• Life cycle
• Damage symptoms
• Identification images

Description

Although outbreaks are short-lived (one to three years), the wide range of host species and ages, and extensive feeding on foliage of any age, results in high levels of mortality in heavily defoliated conifers. Loss of valuable timber, increased fire danger risks, and loss of important wildlife habitat can result from hemlock looper outbreaks. 

Host tree species

The western hemlock looper is a native defoliator of western hemlock, western redcedar, interior spruce and Douglas-fir.

Life cycle

Larvae hatch in the spring and feed lightly during May, June and early July, then heavily from the middle of July to October.

• Biology and history (PDF, 324KB)

Damage symptoms

Damage from western hemlock looper is generally visible in late summer as larvae develop and feed on susceptible host tree species. Looper larvae are known as wasteful feeders because they eat part of all of both old and new foliage.

Defoliation from looper results in browning foliage and fallen needles at the base of the host trees.

Identification images