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City of Burlington Gypsy Moth Control Program Update

Gypsy moth / City of Burlington photo
Gypsy moth / City of Burlington photo

Council members received a memo from Urban Forestry staff (Memo to Council_Gypsy Moth Program_July 30_2020) providing an update to the Gypsy Moth Program as we continue to deal with COVID-19 and its ramifications.

Please click the link above or read further down the information provided in that memo:

At this time of year, one can expect to see gypsy moth having emerged from their cocoons as brown moths flying around erratically, and white moths on tree branches and other surfaces, typically with a brown, fuzzy egg mass nearby. At this stage in their lifecycle, Gypsy moth are no longer feeding so much as reproducing for next year’s cycle of defoliation.

Gypsy moth caterpillar / City of Burlington photo

European Gypsy moth, Lymantria dispar, is an introduced pest that is known to defoliate trees. Caterpillars that emerge in May will feed for several weeks, and in some cases can defoliate whole trees, depending on the population size. Most trees can withstand defoliation of this magnitude over several years as they will ‘push’ a second set of leaves, typically visible around this time (late July).

Repeated defoliation can weaken trees however, as it depletes nutrient stores that would otherwise be used for tree growth, as well as in times of increased plant stress, such as drought, or poor growing conditions.

In order to manage this pest, Egg mass surveys are conducted by Forestry staff in the fall to estimate the relative defoliation that can be expected for the following year. Using an Integrated Pest Management (IPM) approach, areas that are known to have exceeded an action threshold (~2,500 egg masses per hectare) are assumed to be beyond the limits of control by existing predators, such as birds. In these areas, a control such as a pesticide, can be used for the following year, typically in late May. Forestry assesses municipally owned trees only – these are considered along right of ways, parks, and naturalized areas. In 2019, the City applied a pesticide by helicopter to 120 Ha of city-owned land.

Forestry is in the early planning stages of an egg mass survey for the fall of 2020, with the intent to proceed with a program in 2021. Forestry staff will be submitting a budget request to Council for this work, as this program is not currently funded.

If you are interested in control measures for your own home at this time, the recommended option is to conduct egg mass scraping. This can be done most effectively with a hand scraper or barbecue brush. You will be limited to how high you can scrape – but every little bit helps!

For more information, visit or contact us at

Steve Robinson

Manager of Urban Forestry

*Posted by John Bkila, Mayor’s Media and Digital Communications Specialist

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