Some Popular Banff Larch Areas Could Be Less Golden This Fall

Larch season could look a little different in parts of Banff National Park this fall.

Parks Canada says an infestation of larch needleworm is defoliating alpine larches across parts of Banff National Park, leaving some trees reddish-brown, sparse or looking scorched instead of turning their usual bright gold.

The most heavily affected area stretches between the Sundance and Bow mountain ranges, roughly from Healy Creek to Lake Louise.

That puts several popular larch hiking areas within the affected zone, including Healy Pass, Taylor Lake and trails around Moraine Lake and Lake Louise.

Yoho National Park is seeing the same problem, with Parks Canada reporting severe defoliation in several areas, particularly around Lake O’Hara.

So, what’s happening to the larches?

Despite the name, larch needleworm isn't actually a worm.

It’s a native moth, scientifically known as Zeiraphera improbana, whose caterpillars feed on young larch needles.

According to Natural Resources Canada, the caterpillars begin feeding in the spring, initially gathering needles together with silk. As they grow, they attack larger bundles of needles and can eventually strip enough foliage from a tree to make it turn red.

That feeding is what hikers may be noticing now.

Instead of healthy needles progressing toward their familiar fall yellow, heavily affected trees can look brown, thin or scorched.

Are the trees dying?

Parks Canada says they aren’t expected to.

While the appearance can be dramatic, Natural Resources Canada says the damage generally happens early enough in the season for affected trees to produce another set of needles before winter, although those replacement needles can be shorter than usual.

Parks Canada says it is continuing to monitor the current outbreak and assess whether the trees experience any other impacts.

Larch needleworm outbreaks aren't unprecedented in Canada, either. Natural Resources Canada says major outbreaks have occurred in the past, but infestations are generally short-lived and limited in area.

No control measures are currently considered necessary, according to the federal agency.

What this means for larch season

For hikers, the biggest noticeable impact this year may simply be the view.

Some of Banff's best-known larch areas fall within areas that Parks Canada says has been most affected, meaning the usual golden display could be muted or absent in places.

For now, Parks Canada expects the affected trees to survive, even if larch season 2026 looks a little less golden than usual.