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 all phases, approximately 11,000 trees have been removed. In addition, over 50,000 new seedlings of diverse species have been planted through a 3-year donation from Western Forest Products External website, opens in new tab. A total of 58% of Stanley Park’s forested areas have now been treated.
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 3 work for hemlock looper response resumes January 2026
At the Park Board meetings on July 21, 2025, and November 3, 2025, we received approval to advance work in the remaining untreated areas within the internal trail areas of the park.
Work in this last phase will focus on mitigating risk to the public from hemlock looper-affected trees adjacent to trails in the interior of the park, including:
- Lovers Walk
- Tatlow Walk
- Paths around Beaver Lake
Treatments will begin on the west side of the park starting January 13, 2026.
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.
