Hemlock Looper Moths

The western hemlock looper moth is a native species, and is part of the natural coastal forest ecosystem that feeds on trees.

The moths primarily feed on western hemlock, Douglas-fir, and western redcedar trees, but can also be seen on fir and spruce when populations are high.

Hemlock looper moth outbreak

West Vancouver is experiencing a western hemlock looper moth outbreak that started in 2019. The moths are native to this area and outbreaks are normal every 11 to 15 years.

Outbreaks are expected to last three to four years and it is not yet known whether there will be a fourth year as part of the current outbreak. Hemlock looper moths are most noticeable in September and October, when the caterpillars turn into moths.

Populations are dependent on weather and other environmental factors. It is unknown how higher temperatures caused by climate change will impact moth populations in the future.

Western hemlock looper moths cannot make you sick. Residents living near forests should clean the filters of their home ventilation systems to ensure air intakes are functioning properly.

Impact on our forests

Updated August 2021

Trees that were already impacted by the hemlock looper moths have been further stressed by the extreme heat this summer and are very dry. Please do your part to protect our forests by remaining vigilant about the fire risk.

Over-mature trees are more susceptible to damage and may die due to moths feeding on them. This allows younger trees to emerge, and can increase biodiversity and revitalize forests. This is a natural and important process in our ecosystem.

There are no practical measures that can be taken to control the hemlock looper moth outbreak while ensuring the protection of other insects, such as butterflies and other species of moths, which are important to our ecosystem. The outbreak must run its natural course.

The District is working with Metro Vancouver and the province to impacts on our forests and determine potential next steps.

Report tree issues

Dead trees are more likely to be uprooted by wind than healthy trees, however, trees could remain structurally sound many years after their death and are typically not imminent threats unless there is extensive root rot or other issues with the tree or site. 

If trees are within striking distances of homes or yards, it is recommended that homeowners get danger tree assessments completed or have an arborist do an assessment. A geotechnical engineer should be consulted to assess slope stability.

If you notice trees that appear to be dead or hazardous on District property, please report it:

Report a Problem