Black army cutworms in Jasper National Park

Spring 2025

The 2024 Jasper Wildfire has made significant changes to the landscape of Jasper National Park. One of these changes is the presence of black army cutworms, a native moth species whose larvae thrive in recently burned environments.

These insects are a natural part of the forest’s post-fire recovery. When the wildfire cleared vegetation from the forest floor, it provided the perfect setting for adult moths to lay their eggs. This spring, those eggs hatched into larvae that are now feeding on newly emerging plants. While their sudden presence may be surprising, black army cutworms pose no threat to pets or people and are not harmful to the long-term health of the ecosystem.

What visitors can expect

High numbers of caterpillars

Small, dark larvae may be visible in and near burned areas, including Whistlers Campground. Some larvae have also been spotted near Pyramid Bench.

Visible plant damage

Temporary leaf damage (often seen as small “shot holes”) is common. Cutworms mainly feed on herbaceous plants but can also consume young conifer seedlings, including pine, spruce and Douglas-fir.

Short-lived impact

Cutworm populations typically peak one to two years after a fire. They prefer dry, sunny slopes and naturally decline as vegetation recovers.

Impacts on restoration efforts

Parks Canada’s ecological restoration teams are closely monitoring cutworm activity throughout the park. In areas with high cutworm presence, replanting efforts may be postponed by a season or two to protect young seedlings from defoliation. Restoration will prioritize north-facing slopes, which are cooler and moister - conditions less favourable to cutworms.

Visitors recreating in recently burned areas should avoid disturbing any recovering vegetation by staying on designated trails. This helps reduce impacts to sensitive regenerating areas that may be already affected by cutworm larvae feeding.

Learn more about black army cutworms