Town of Oakville taking action to control gypsy moth infestation

Thursday, April 29, 2021

Based on population surveys conducted in 2020, Oakville faces extreme levels of gypsy moth infestation this year that could affect 102 hectares (252 acres) of town woodlands and result in a significant loss of trees if no action is taken. In mid-May, the town will be conducting an aerial spray in 15 town woodlands with a safe and naturally occurring pesticide to control the gypsy moth infestation.

“The town’s tree canopy is one of our greatest assets. Oakville and our neighbouring municipalities successfully conducted aerial sprays in targeted areas in 2008 and 2018. We will continue to protect our urban forest from these damaging invasive insects before they cause irreparable damage,” said Mayor Burton.

Aerial spraying will occur most likely in mid-May once the gypsy moth caterpillars have emerged. Spraying will be performed by a low flying helicopter, between 5 and 8 a.m. Two treatments will be necessary within a few days of each other. Additional ground spraying may occur during the same period to target town trees adjacent to woodlands that have been identified as high-risk for gypsy moth presence.

Aerial spray dates are highly dependent on weather conditions and may need to be postponed with little notice. Once dates are confirmed, they will be posted on our Gypsy Moth page and the town’s Facebook and Twitter accounts. Residents who live in the near vicinity of any of the town woodlands that will be treated and would like to receive 48-hour email notification of the spray can send an email, providing contact information, to

The designated woodlands and trails will be closed temporarily during the spray and reopen immediately after. Some roads may be closed briefly as the helicopter passes. Aerial spraying will not take place over town streets or residential properties.

No special precautions are required for residents near the spray areas. Residents may wish to alter their early morning plans such as running or dog walking on spray days or, if preferred, remain indoors and close windows during the spraying. There may be some temporary noise associated with the low flying helicopter. There are no health concerns with entering the woodlands after trees have been sprayed.

Municipalities have successfully conducted aerial spray programs using the safe pesticide, Bacillus thuringiensis Kurstaki (Btk) for decades. It has replaced chemical insecticides in aerial spraying programs worldwide.

The use of BtK is approved by the Health Canada Pest Management Regulatory Agency and is permitted under Oakville's pesticide-bylaw.

BtK has no negative environmental or human health effects. BtK is a bacteria which occurs naturally in soil. The bacteria is poisonous only to a certain group of insects when ingested during their larvae or caterpillar stage. BtK does not affect adult moths or butterflies or other beneficial insects such as honeybees, or pets, birds, fish, or mammals. Learn more about BtK on Health Canada's Btk Fact Sheet (pdf) and on Natural Resources Canada's website.

Public safety and the health of our environment are top priorities at the Town of Oakville. We understand there might be some inconvenience on the mornings the aerial spray takes place and we appreciate your patience and cooperation.

For more information visit our Gypsy Moth page.

For any questions please contact ServiceOakville at 905-845-6601 or