Several London, Ont. green spaces targeted for aerial pesticide spray

Several local green spaces, including Springbank Park and the Thames Valley Golf Course, will be subject to an aerial pesticide spray toward the end of May as city officials look to protect trees in London, Ont., from spongy moths.

Formerly known as the European gypsy moths, spongy moths wreak havoc on trees, but they haven’t always required the intervention of an aerial spray.

Last year marked the first time in more than a decade that city officials conducted an aerial spray in London.

“Based on the data we’re collecting, it shows that several of our parks are again going to experience a significant amount of defoliation,” said London’s urban forestry manager Jill-Anne Spence.

“Tree can tolerate some defoliation for a couple years, but the amount of defoliation we’re seeing is between 80 to 100 per cent, so this is an effort to ensure that we’re protecting these tree assets and all the benefits that they provide.”

Spence says there’s been a record-breaking amount of spongy moths observed in London and all of Ontario.

1:48 Southern Ontario bracing for another spongy moth outbreak

Between every eight to 10 years, the spongy moth population will build up in the environment with natural controls, such as natural predators and pathogens, causing the population to collapse about three years before the infestation hits its peak.

“What’s unique about this infestation is just the significant amount of defoliation that we’re seeing,” Spence added.

According to the Ministry of Natural Resources and Forestry, spongy moths caused 586,385 hectares worth of defoliation throughout Ontario in 2020.

Last year, that number shot up nearly 1.8-million hectares.

Also in 2021, defoliation caused by spongy moths was found to be the most severe in forest stands that contain species of oak, maple, poplar, willow and other broadleaf trees.

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Spence says Londoners can also take matters into their own hands if they’re worried that trees in their own yard will be chewed by the destructive pest.

One prevention method is to scrape egg masses, which look like tan splotches about the size of a quarter, off trees into soapy water. Burlap barrier bands can also be used to collect the caterpillars as they move up and down the trunk of the tree. Year-round trapping tips are available on the city’s website.

Spence says it is also extremely important to not move firewood, particularly from a place that has spongy moths to a place that doesn’t.

“Not only spongy moths, but also things like emerald ash borer, asian long-horned beetle – that is a way that these pests can travel far and wide and quickly, more so than if they were left to their own devices,” Spence said.

As for the upcoming sprays, they’ll target Springbank Park, Fairmont Park, Somerset Woods, Forest Hill Woods and Thames Valley Golf Course.

The timing of the first spray is weather-dependent, but is expected to take place between May 23 and May 28, with a second spray taking place seven to 10 days thereafter.

The confirmed spray date will be posted to the city’s Get Involved website 48 hours in advance.

— with files from Global’s Matthew Trevithick