Town of Oakville taking further action to control LDD moth infestation

At last night’s meeting, Oakville Town Council took a significant step towards saving our tree canopy by approving funding in the amount of $165,000 from Capital reserves to remove LDD (Lymantria dispar dispar or Gypsy moth) eggs from over 2,300 municipal trees this fall. Similar to many municipalities across Ontario, Oakville was significantly impacted by LDD infestations in spring 2021 and preventative action now will help curb next year’s infestation.

LDD moth is a non-native insect that is considered a major destructive pest in North America. The larvae or caterpillar stage of this insect causes tree destruction by feeding on the leaves of oak and other deciduous trees. After repeated defoliation, trees may die or become so weakened that they are vulnerable to other pests or disease.

“The town’s tree canopy is one of our greatest assets and ongoing efforts are required to preserve it. Preventative actions this fall will further protect our urban forest from these damaging invasive insects next spring,” said Mayor Rob Burton.

In an effort to decrease the significant LDD population in Oakville, the town conducted an aerial spray this past spring and for the first time will be implementing a large-scale egg scraping program this fall. Although hand scraping of egg masses from tree leaves is a labour-intensive method of population control, it is the only viable option to be implemented in the fall and winter months to decrease the LDD population the following year. Aerial spraying is only effective in the spring when the caterpillars emerge from their eggs.

With an extendable pole pruner equipped with a scraper, the town’s tree service contractors can reach as high as seven meters up a tree to remove LDD egg masses, reducing the cost for an aerial truck and the need to climb trees.

“This year was one of the highest recorded populations of LDD moth in the province in the last 30 years. According to the latest defoliation and egg mass survey conducted by the town, there are areas of concern that could see another year of heavy LDD infestation in 2022. More and more residents are calling the town to find out how they can protect their trees. Acting now will help reduce next year’s population levels,” said Chris Mark, director, Parks and Open Space.

The town has had a comprehensive monitoring and mitigation program for LDD moth infestations since 2005, and has conducted aerial sprays of a safe and effective bio-pesticide in different locations around town to great success in 2008, 2018 and 2021.

Other mitigation efforts conducted by the town include ground spraying of individual trees, and distribution of tree banding kits to homeowners residing within the highest infestation areas. The town is investigating the possibility of providing tree banding kits to residents residing in the high infestation areas in advance of the 2022 hatch out season. Tree banding is a viable option for a select number of high value trees, but is not practical for large areas of trees or in woodlands.

Here’s what residents can do to protect their trees and help control the spread:

The Forestry section will present a report to the town’s Budget Committee in November, including a budget for another potential aerial spray to further reduce LDD moth populations in 2022.

For more information, review the staff report, item 9.4 on the August 9 Council agenda, or visit our LDD Moth page.