On May 25, 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. The gypsy moths eat the leaves of trees, causing 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 identified for spraying include:
City staff will be stopping traffic on roads nearest the park while the helicopter is spraying. The road closure will take 15 minutes or less.
An interactive map is available on burlington.ca/gypsymoth that allows residents to enter an address so they can see where the address is in relation to the spray areas.
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“The weather forecast shows good conditions for the aerial spraying and the gypsy moth larva are at the right stage in their development for the treatment to have maximum impact on them. A successful reduction in their number will help protect the health of our trees and the environment which is a win for everyone,” said Steve Robinson Burlington manager of Urban Forestry.
- The City’s contractor will be applying a Class 11 biopesticide, with active ingredient Bacillus thuringiensis ‘kurstaki’.
- Application of the pesticide with be completed between 5 and 7:30 a.m.
- 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 due to larval 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.
- European Gypsy moth, Lymantria dispar, is a non-native invasive pest that was introduced in the late 19th century. It was first discovered in Ontario in the 1960’s and has been a major defoliator of deciduous and coniferous trees across Southern Ontario.
- 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 last conducted a similar program in 2019. Program frequency is determined as part of the city’s Integrated Pest Management (IPM) program.