Swarms of western hemlock looper moths invade parts of B.C. south coast

If you think there are a lot of moths around right now, you’re correct.

Parts of B.C. are seeing an infestation of the western hemlock looper moths this year, with thousands more of the insects than normal flying around.

“We’re at mostly what we would consider to be peak flight right now, with lots of moths around and some significant tree mortality starting to show up in the forest,” Jesse Montgomery, environmental manager for the regional district of Metro Vancouver, told Global News on Thursday.

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The infestation is no surprise to him. Staff noticed a large number of moths in late summer last year, he said, so they were anticipating a larger number of the western hemlock looper.

The moths primarily feed on western hemlock trees when they are in their caterpillar stage, but if there are not enough of those trees around, they will attack Douglas firs and cedars.

“The mortality this year became most notable probably in early August, once we started to see some dry weather,” Montgomery said.

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Some trees will die while others will be more resilient, he said, adding the death of some trees isn’t necessarily a bad thing because it makes way for younger, newer growth.

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Metro Vancouver will continue to monitor the water quality and forests as the infestation continues.

The moths are not going anywhere just yet. They’re still highly visible in areas such as Vancouver’s North Shore and Coquitlam.

“It’s a naturally occurring species and outbreaks are common and known to this area, typically happening in approximately 10- to 30-year cycles. We did have a significant outbreak in our Coquitlam water supply area in the early 2000s,” Montgomery said.

In other words, it might be around the year 2040 before we see these swarm sizes again.