The ongoing gypsy moth invasion is stressing Oakville’s trees and distressing its residents.
That’s the conclusion of town staff, who have developed a $165,000 plan to scrape egg masses off about 2,400 local street trees this fall.
The moths, now being referred to as LDD (Lymantria dispar dispar) to leave behind the ethnic slur, appeared in record numbers in 2021. They feed on the leaves of oak and other deciduous trees, resulting in defoliation that can cause serious tree damage.
The town received 476 service requests related to the pests in 2021, with 336 of those calls requesting expanded spraying and treatment options.
Based on site inspections, town staff fear heavy infestation will remain a problem in 2022.
To attempt to control this year’s infestations, the town undertook aerial spraying of 102 hectares of municipal woodlands, applied ground spray to 162 high-value oak street trees, and distributed 200 tree banding kits to private homeowners in the areas most heavily infested.
While similar plans are in place for next summer, the manual scraping program will enhance control measures. Egg masses will be removed from the lowest seven metres of the main trunk of trees.
“Egg mass scraping is an effective but labour-intensive method of LDD population control,” says the report from town staff. “It is the only viable option to be implemented in the fall of 2021 and winter 2022 to decrease the population of next generation of LDD.”
The town will also seek to purchase additional tree banding kits, which were limited in availability this year due to pandemic supply chain challenges.
According to the report, tree banding can be effective in reducing the number of LDD caterpillars. The bands are applied about five feet up on the main stem to catch caterpillars during their daily migration from the ground to the canopy.
Town council approved the mitigation plan during its Aug. 9 meeting.
“This report speaks highly to the importance that we place on our canopy and the efforts of staff,” said ward 3 councillor Dave Gittings.
Several resources are available online to demonstrate how residents can remove egg masses from trees on their property. Egg masses can be removed from trees between September to April to reduce next year’s infestation.