This year’s Western hemlock “looper” moth outbreak has been seen in the Lower Mainland and the Interior, including communities throughout the Columbia Shuswap Regional District. (Lorraine Maclauchlan photo)

Moth outbreak prompts concerns for forest health

Shuswap entomologist argues looper moth resurgence beneficial to biodiversity

As with the butterfly, the flapping of the Western hemlock moth’s wings is not without wide-ranging implications.

An outbreak of the native moth species is being reported in the Lower Mainland and in the Interior, including communities throughout the Columbia Shuswap Regional District.

Lorraine Maclauchlan, a B.C. forests ministry entomologist, said outbreaks of the moth occur about every nine to 11 years in the Interior, and every 10 to 20 years along the Coast, and usually last between two and three years.

“The larvae – commonly called loopers or inch worms – feed from June through August and can strip trees of their foliage in a single season, sometimes killing large swaths of forest,” Maclauchlan explained in an email. “The moths emerge in September and can be seen in trees, on the ground and resting on tree trunks until early October. The moths are mating and laying eggs during this time.”

Outbreaks of the moth typically occur in hemlock stands, but occasionally they will erupt among stands of Douglas fir – something that has been seen this year. The outbreak is expected to increase in size next year, and the province is concerned about the impact it will have on Douglas fir stands.

“These outbreaks are a natural part of the forest ecosystem…,” said Maclauchlan. “This outbreak is a concern because it may kill or weaken an already susceptible and highly pressured forest resource – both from a habitat and timber production standpoint.”

Maclauchlan said high numbers of the moths are being seen in the Clearwater Lake area, the North Shuswap, Mabel and Sugar lakes and around Kamloops, among other areas, and the province is currently surveying and assessing sites for consideration of targeted control programs next summer using the biological insecticide Btk (Bacillus thuringiensis), which targets the larvae. Maclauchlan said Btk has been used by the ministry for past outbreaks in high priority areas, to protect critical habitat and key Crown land.

Outbreaks were likely not as extensive in the Shuswap in the past, said Maclauchlan. However, along Highway 1, east of Revelstoke (where the current outbreak is also occurring), Maclauchlan said you can see evidence of past looper-caused mortality, where large areas of forest were killed.

The last outbreak, she said, occurred around 2011-12 in the Revelstoke drainage and near Serpentine River (Blue River), and was not as large.

“Most outbreaks are away from towns and major roads so are not visible to the public,” said Maclauchlan. “This outbreak is a bit different in that it is in lower elevation fir stands.”

North Shuswap resident Jim Cooperman believes the outbreak to be far larger than what might be deemed normal, as he has never seen so many moths in Douglas fir stands.

Read more: Tussock moth infestation in Cariboo is farthest north ever recorded in B.C.

Read more: Insects disappearing

Read more: New study is first full list of species that only exist in Canada

“Consequently, there should be concern that this large outbreak may be related to climate change, and like the pine beetle explosion, which also did not conform to existing scientific knowledge, it could lead to the death of too many trees,” said Cooperman, adding this could lead to many more problems, including increased fire risk, increasing the number of fir bark beetles thus leading to more dead trees and impacts to water supplies.

“No one would want to see our Douglas fir forests die.”

Salmon Arm entomologist Art Borkent takes a more holistic view of the Western hemlock moth, noting it is one of the thousands of insects that play an important role in supporting the biodiversity of healthy forests.

“There is a relationship between these trees and their pests and it’s an evolutionary relationship,” said Borkent. “There’s the battle between species, between refining what they are and their response to attacks, whatever it is – (they) develop resistance…

Borkent said trees impacted by the moth can become deformed, providing excellent habitat for other insects and for birds.

“And, in the meantime, where insect populations have crashed, we suddenly have a species with larvae all over the place. There’s a whole bunch of birds out there going, whew!” said Borkent.

As with past Western hemlock moth outbreaks, Borkent said the current one will run its course.

“The looper has been here for millions of years… It has its own parasites, its own regulators, and the population will build like this maybe two years, maybe even three, and then boom, they get nailed. And they become very rare.”

Like us on Facebook and follow us on Twitter

Shuswap Lake

Get local stories you won't find anywhere else right to your inbox.
Sign up here

 

A Western hemlock moth caterpillar. (Lorraine Maclauchlan photo)

This year’s Western hemlock “looper” moth outbreak has been seen in the Lower Mainland and the Interior, including communities throughout the Columbia Shuswap Regional District. (Liam Harrap-Revelstoke Review)

Just Posted

A map of the proposed location for the temporary workforce camp in Johnson Heights that is subject to a Temporary Use Permit from the city. (City of Revelstoke)
City council approves permit for worker camp in Johnson Heights

The permit was issued for two years in a close vote

There has been COVID-19 exposures at two elementary schools in District 42. (Image courtesy CDC)
Interior Health reports 24 additional COVID-19 cases

This includes three school exposures in Kelowna

Revelstoke Tim Hortons staff give a $3,139 cheque to Hannah Whitney and Jake Sloots (left side of cheque) from Community Connections. (Submitted)
Revelstoke Tim Hortons raises $3K for local food bank

The funds were do to the Smile Cookie campaign from Sept. 14 to 20

Revelstoke Mountain Resort has released additional details about upcoming winter operations. (Liam Harrap/Revelstoke Review)
Resort releases more details on upcoming operations

Opening day is scheduled for Nov. 27 in Revelstoke

The new traffic circle in Revelstoke will open Oct. 29. (Submitted/City of Revelstoke)
Roundabout to open Oct. 29

Ribbon cutting details to be released

Provincial health officer Dr. Bonnie Henry arrives for briefing on the COVID-19 situation, B.C. legislature, Oct. 26, 2020 (B.C. government)
B.C. records 217 more COVID-19 cases, mask use urged

Infection spike continues, 21 senior facilities affected

Los Angeles Dodgers celebrate after defeating the Tampa Bay Rays 3-1 to win the baseball World Series in Game 6 Tuesday, Oct. 27, 2020, in Arlington, Texas. (AP Photo/David J. Phillip)
L.A. Dodgers beat Rays 3-1 to win 1st World Series title since 1988

National League champs claim crown in six games

(Brennan Phillips - Western News)
UPDATE: Flames doused for second time at fatal Penticton apartment fire

The Elm Ave. building first caught fire around 4 a.m., killing two people and displacing dozens

Two have been taken to hospital following a vehicle crash north of Vernon on Highway 97 Tuesday, Oct. 27, 2020. (Brendan Shykora - Morning Star)
Crash north of Vernon causes Highway 97 traffic delays

Emergency crews respond to two-vehicle incident near Swan Lake; occupants taken to hospital

Seven-year-old Aaliyah Rosa was found dead in an apartment in Langley in July. (Langley Advance Times files)
Child’s body cold, no pulse: Off-duty cop testifies in Langley mother’s murder trial

The seven-year-old girl’s mother faces a first-degree murder charge

Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

(Submitted)
Penticton apartment fire claims two lives

An apartment on Elm Avenue went up in flames Tuesday morning

A Summerland woman has set up an online fundraiser to provide backpacks to those being released from correctional facilities.(ca.gofundme.com)
Summerland woman raising money for backpack program

Backpacks will be distributed to those being released from correctional facilities

École de l’Anse-au-sable. (Google Maps)
15 cases of COVID-19 tied to Kelowna Francophone school outbreak

Three other schools in Kelowna are also dealing with potential exposure events

Most Read