Western Hemlock Looper Management

Predictive sampling techniques

Egg sampling is carried out in the fall when defoliation has been noticed, or when an outbreak is anticipated, to predict levels of defoliation the following summer.

Long-term strategies

Well-spaced, even-aged, thrifty stands should be less susceptible and suffer fewer impacts from western hemlock looper defoliation. Promoting mixed-species stands with less than 50 per cent western hemlock, avoiding cedar-hemlock mixes, and preferring non-host species will also reduce susceptibility. Stand-tending treatments such as spacing and fertilization will help maintain a healthy and more resilient stand.

Short-term strategies

The recommended short-term strategy is to identify high-hazard stands containing the highest historical frequency of infestations, and monitor in years preceding an anticipated outbreak. In eastern Canada,  Bacillus thruringiensis var. kurstaki (Btk) has been sprayed on outbreaks to control them. In British Columbia two formulations of Btk were tested in 1993 and shown to control the western hemlock looper effectively and this information was used to obtain registrations for use against the western hemlock looper. Some chemical insecticides are also registered for use in B.C. but have not been applied operationally to protect Crown forests.