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
Stanley Park is experiencing a hemlock looper External website, opens in new tab outbreak which has damaged many of its trees, including western hemlock, Douglas fir, and grand fir.
A significant portion of the park is affected, particularly near Lions Gate Bridge. 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 are more vulnerable to the hemlock looper outbreak and less likely to recover.
Managing the hemlock looper outbreak and wildfire risks
Hemlock looper populations usually decrease when the weather isn't suitable for their life stages and when there are more predatory insects like parasitic wasps around to eat them.
Using pesticides is not an option because they harm other, non-target insects that live in the forest ecosystem.
We're addressing the outbreak and wildfire risks with support from a forestry consultant whose recommendations are expected in mid-2023. They will provide a report that outlines a long-term approach focusing on risk mitigation and ecological enhancements for long-term forest health.
In the meantime, we will continue to manage dead and dry trees that present public safety and wildfire risks.