

About the moth
The hemlock looper moth is an endemic insect that experiences population outbreaks approximately every 15 years.
Its larvae hatch in the spring and aggressively feed on foliage, causing the most damage between July and October.
It feeds on coastal coniferous species which makes Stanley Park particularly vulnerable.
Hemlock looper moth outbreak
In 2020, Stanley Park experienced a hemlock looper External website, opens in new tab outbreak.
Though 160,000 of these trees were affected — including western hemlock, Douglas fir, and grand fir — only a fraction of these trees are a risk to public safety and will need to be cut-down.
As part of our progress in phase 1, less than 8,000 trees were removed, which addressed 25% of the total affected forest area.
This outbreak also affects parts of West and North Vancouver, where many trees are dying.
After recent droughts and hard winters, trees in Stanley Park were more vulnerable to the looper outbreak and less likely to recover.
What's happeningPhase 2 hemlock looper response has resumed
Treatments have begun along the west side of Stanley Park Drive, with removal work expected to be complete by mid-March. Planting and restoration will follow.
All work continues to be carried out by qualified environmental professionals contracted to deliver this work in accordance with current municipal, provincial, and federal regulations, including the Migratory Birds Convention Act (MBCA), which protects nesting birds and their habitats. As outlined in the City of Vancouver Bird Friendly Landscape Operational Guidelines PDF file (9.5 MB), where maintenance is required, bird nest surveys are conducted prior to vegetation management and tree removal activities.
Where work is taking place in the park leading up to and during the bird nesting window, registered professional biologists (RPBio) conduct bird nesting surveys to identify any active nests or nesting behaviour.
Managing the hemlock looper outbreak and wildfire risks
Hemlock looper populations usually decrease when the weather interrupts their life stages and when predators such as parasitic wasps and birds eat them.
Using pesticides is not an option because they harm other, non-target insects like butterflies that live in the forest ecosystem.
We're addressing the outbreak and wildfire risks with support from a forestry consultant. Their expert report PDF file (4 MB) outlines a careful approach, focusing on risk mitigation and ecological enhancements for long-term forest health.