Gypsy moth aerial spraying to take place tomorrow - Wednesday

News 100 redBy Pepper Parr

May 28th, 2019



Tomorrow, Wednesday, May 29th, the City of Burlington will be using a low-flying helicopter to apply a bio-pesticide over four wooded areas to control gypsy moth populations. This pest causes significant defoliation and potential long-term impact to the City’s urban forest.

Application of the pesticide will be completed between 5 and 7:30 a.m. and is expected to take 5-10 minutes for each park.
The areas include:

• Forestvale/Kerncliff Park
• LaSalle Park
• Lowville Park
• Mountainside Park

aerial spraying gypsy moth

Said to be safe – the aerial spraying is necessary to caterpillars from eating leaves off trees.

Updates will be posted on the City’s Twitter and Facebook accounts @CityBurlington and online at
The City’s contractor will be applying a Class 11 biopesticide, Foray 48B, REGISTRATION NO. 24977 PEST CONTROL PRODUCTS ACT, with active ingredient Bacillus thuringiensis ‘kurstaki’.

About the Biological Pesticide
Bacillus thuringiensis ‘kurstaki’ (Btk) is a soil-borne bacterium that is applied to the leaves of affected trees while caterpillars are in their early stages of development. Once ingested, the bacterium disrupts the caterpillars’ digestive system with cessation of eating within 24-48 hours. Within days, caterpillars that have ingested Btk will succumb to its effects.

Btk does not have any negative effects to humans, birds or bees. Btk will affect other caterpillar species (known as non-target species). Due to its low residual nature and the narrow spray window of pest development, the non-target impact is expected to be low.

Individuals who have concerns should take reasonable precautions to avoid exposure during a spray program in the same way they would avoid pollen or other airborne materials during days when air quality advisories are issued. Residents can also reduce exposure by staying indoors with windows and doors shut during the spray period if spraying is taking place in their area, although this is not required by health officials.

As part of Burlington’s Integrated Pest Management (IPM) program, Forestry staff assess sites annually across the city and conduct egg mass surveys to determine areas that have exceeded an action threshold, whereby natural processes can no longer maintain pest population levels on their own. Although healthy trees can generally withstand defoliation several years in a row, trees which are already in distress from problems such as acute drought, compacted soils, diseases or other pests, may decline and die. Generally, healthy trees which are defoliated in spring, will leaf out again by mid-summer. Gypsy moth populations tend to be cyclical, with peaks every 8-12 years, followed by dramatic population decline of the pest.

The City of Burlington conducted a similar program in 2008.

For questions or concerns, please contact Brianna Thornborrow, Supervisor of Forest Planning and Health at or 905-333-6166, ext. 6145.

Steve Robinson, Manager of Urban Forestry explained that “Taking action now means protecting our trees both in the short-term and for the long-term. We are working with all authorities including emergency services, the Ministry of Transport and the Ministry of the Environment, Conservation and Parks to ensure a safe, fast and coordinated application to minimize disruption and maximize effectiveness.”

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1 comment to Gypsy moth aerial spraying to take place tomorrow – Wednesday

  • Sally Hewitt

    What about the wildlife and birds living in these areas? Is there any risk from this spray?
    Birds eat caterpillars and I am sure some wildlife eat caterpillars…how will they be affected?

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