Aerial view of the Stanley Park forest, surrounded by water

Stanley Park forest management

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 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 will resume in early January

Recent weather events in October and November 2024 impacted trees across the park. Dead trees in untreated areas of the park are deteriorating much faster than anticipated, outpacing the phased plan for risk mitigation and restoration.

At the Park Board meeting on December 9, 2024, we received approval to advance work in high-priority untreated areas along the west side of the park. Treatment will focus on Stanley Park Drive, North Lagoon Drive, the remaining seawall portion, and the trails, which will remain closed to the public until further notice.

The week of January 6 will involve relocating the site trailer, processing logs, and storing equipment in the third beach concession parking lot. Treatment will begin the week of January 13, 2025.

Review traffic impacts

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 (4 MB) outlines a careful approach, focusing on risk mitigation and ecological enhancements for long-term forest health.