By Lisa Houle | December 10, 2024
Crunch, crunch, crunch.
This distinctive sound is ingrained in the memories of Daryl and Marilyn Logan. In 2020, a wave of invasive spongy moths descended on Ontario. They’ll never forget the sound of millions of caterpillars chewing and decimating the trees all around them.
The Logans lived on a 20-acre rural property in the Mulmur Township of Mansfield, Ontario for 32 years before moving to Salt Spring Island, B.C. in 2021. The firsthand account they recently shared with ISCBC – of the devastation caused by a spongy moth infestation, is a powerful, cautionary tale.
ISCBC: What was the landscape like around you in Ontario?
D&M: “In all the Ontario cities we lived in, there was an abundance of tree canopy. These were mostly the deciduous trees typical of Ontario (several types of maple, oak, ash, beech, some surviving elm, and assorted fruit and nut tree varieties). Mulmur Township had a mix of rolling hills, deciduous forests, and marginal farmland.
Of our 20 acres, 12 acres were mature ‘edge of the Carolinian’ forest [deciduous forest rich in unique flora and fauna, with species not found elsewhere in Canada], and eight acres were mainly pasture with a few plots of trees. Many trees in the forest were well over 100 years old. It was predominantly a sugar maple stand – and yes, we made our own maple syrup – with a mix of red maple, beech, ash, ironwood, basswood, and a few yellow birch. A small swampy area supported an abundance of eastern white cedars. Assorted maples, ash, elms and wild fruit trees grew along the roadsides, mostly planted by early pioneer families.
Shortly after moving to the property, we took a woodlot management program from a local college to understand the needs of our forest and received official “Managed Forest” status from the Ontario Ministry of Lands & Forest. In the more open areas of our property, we planted approximately one acre of mixed pine and spruce trees to act as a windbreak, red maples along our 100-yard-long driveway, and oak, maple, and linden in our front yard.”
ISCBC: How did you discover spongy moth was a concern?
D&M: “In all our years of living in Ontario, we had never been aware of the spongy moth being so destructive until 2020. Looking back, it had been building – in 2020 they just overwhelmed the trees in our area. It was devastating. The moths targeted our front yard oak trees first, completely stripping their leaves. The maples and other hardwoods were the next targets.”
ISCBC: Can you describe what it was like to experience the destruction?
D&M: “For weeks, the caterpillars hatched and started consuming the leaves. Every day we would sweep large batches of caterpillars into buckets of soapy water and scrape off any egg sacks we could find into the same buckets. We used a corn broom to stab and squash caterpillars against the tree bark.
We wrapped trees with overlapped burlap to trap caterpillars that were crawling up from the ground. We encircled numerous trees with duct tape, twisting the final layer with the sticky side out to deter caterpillars from crawling up into the canopy. We discovered that touching the caterpillars caused skin irritation (itch and rash), so we kept rubber gloves in our pockets as the need to deal with them was relentless.
When the caterpillars – then moths – finally passed, there were the eggs to deal with. They were everywhere! We knew what was coming next, so we spent months scraping egg sacks off the trees. This was just around the house. We could do nothing about the forest area because the moths/caterpillars were high in the canopy.
Day by day you could see the impact from our home – the steadily reducing amount of leaf canopy in the forest. It was eerie to walk through the forest while there were millions of caterpillars eating leaves simultaneously. There was a constant crunching sound. Although it sounded like a chewing noise, it was more likely the noise of caterpillar excrement hitting the leaves on the forest floor.”
ISCBC: How did spongy moth change the landscape?
D&M: “Once the wave of caterpillars passed and the canopy of leaves in the forest was devastated, the forest floor changed. Presumably this was due to more light coming through to the ground. There were species of vegetation that seemed lost and new species emerged that we had never seen before. We really noticed the spread and height of this new ground cover.
In our case, it was strictly our deciduous trees that were affected. The maples and oaks did recover some of their canopy by the fall but were clearly weakened. Our neighbours, who had fewer deciduous trees and larger coniferous plantations, found that the spongy moths attacked them as well. They lost many trees. While deciduous trees can usually recover from a year or two of attacks, the coniferous trees that were affected died as a result of their needles being eaten.”
ISCBC: How did your community rally in response?
D&M: “Community support was significant as no properties were spared. When neighbours learned about the possibility of aerial sprays for their yards and forests, those with abutting properties connected to arrange for spraying the following spring.
We were part of this effort but moved to Salt Spring in the middle of winter. The purchasers of our property did carry through with spraying. It was an expensive process and there was no public financial support for the spraying (or control of any kind). Some people could not afford to have it done, but we were not aware of anyone – including organic farmers – who did not support the effort. We had to educate ourselves and find a course of action. Many neighbours proceeded with the spraying and, while not completely successful, it was a huge improvement.”
ISCBC: What would you say to people who aren’t convinced invasive species pose a real threat to the environment?
“We didn’t have that experience in Mulmur, at least not after the moths had consumed tens of thousands of acres of deciduous forest. Anybody who witnessed this invasion was appalled at the destruction. We were on our own to deal with it, educate ourselves, and find the right course of action – as a bonus, it brought the community together!”
ISCBC staff met the Logans on Salt Spring Island in 2023, where they attended a public open house about spongy moths and the local project to be undertaken to survey for them.
“Daryl and Marilyn were there because they had experienced the destruction from spongy moths first-hand,” said Nick Wong, Science and Research Manager at ISCBC. “They put great effort into saving their trees and helped decrease the population of spongy moths using several tactics. They did what they could, and we consider that a success.”
You can do your part to stop the spread of invasive spongy moths. When travelling or moving from areas with spongy moth detections, thoroughly examine all outdoor items for signs of live insects or egg masses. Only Buy Local Burn Local Firewood to ensure invasive species are not accidentally moved in firewood. Following a few simple best practices can make a big difference.
If you find spongy moth egg masses, caterpillars, or adults, ensure you wear gloves while handling them. Take several photos of the specimen and report any suspected spongy moth immediately by using the mobile Report-Invasives-BC app for Apple and Android platforms, available for download. You can report any invasive species through the ISCBC website, emailing info@bcinvasives.ca or call 1-888-933-3722.
Lisa is a Communications and Outreach Coordinator at ISCBC. She values a diverse environment and connecting with others about environmental protection. In her spare time Lisa enjoys spending time at the ocean and beach combing for sea glass. You can reach Lisa at lhoule@bcinvasives.ca
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