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City reminds residents about monitoring and managing gypsy moths on their properties

Updated June 15, 2020

With the warm weather now here, Londoners may be seeing common insects and pests that arrive with the summer. In certain parts of the city, gypsy moth caterpillars are emerging from their egg masses as part of their lifecycle. 

The City of London’s Forestry Division continues to manage gypsy moth populations on City trees, and is providing the following information to help residents monitor and manage trees and pests on their private properties.

What is a gypsy moth?

The non-native invasive European Gypsy Moth is a major forest pest concern because the caterpillar, or larva stage of the insect, eats the leaves of trees, defoliating them. This makes them more susceptible to disease and damage from other insects, like tent caterpillars.  Continued yearly defoliation of trees can lead to their decline and eventual death.  

During the larval or caterpillar stage, a single gypsy moth caterpillar can eat an average of one square metre of leaves.

How is the City managing the gypsy moth population?

As part of the London’s Integrated Pest Management approach (IPM), the City uses various management techniques to address the pest population, starting with the least harmful to the environment.

In fall 2019, Forestry staff assessed and surveyed the egg mass and gypsy moth populations on City trees, in parks and along boulevards. Several locations in the Byron area were identified to have high egg mass populations and this past winter, egg masses were removed on more than 6,000 trees. The gypsy moth is well established in southern Ontario. The goal of the City’s IMP program is to reduce the gypsy moth population to within acceptable numbers.

Based on the information gathered during the surveys and ongoing monitoring by staff, aerial spraying is not part of the IPM approach at this time. Forestry staff will continue to monitor gypsy moth populations and their impacts on City trees to determine future approach to managing the pest.

What can residents do to protect their private trees and property from gypsy moths?

Becoming familiar with the gypsy moth’s lifecycle will help manage its spread. There are four main stages of the gypsy moth lifecycle: larva/caterpillar, pupa, adult moths, and egg masses. We are now in the larva/caterpillar stage.

Residents can take action to remove gypsy moths on their properties to reduce the risk of infestation as caterpillars grow larger, and later in the summer, turn into moths and begin to breed.

To manage the gypsy moth population, homeowners can:

  • Handpick them from smaller trees and plants.
  • Transition to burlap tree wrappings as they grow larger this summer.
  • Once captured, gypsy moths at any stage should be drowned in soapy water.
  • Consult with a licensed contractor to explore biological pesticide sprays or tree injection options.

Step-by-step instructions to wrap burlap around trees and capture the caterpillars, along with more options for managing gypsy moths at various times of the year can be found at

Can people experience reactions to the gypsy moth?

Some people may experience a reaction to any caterpillars’ “hair” or setae, including the gypsy moth. If you are experiencing any sort of physical reaction, please contact your family care physician for medical advice.


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