Gypsy Moths

Gypsy Moth Caterpillar European Gypsy Moth populations have been increasing in Ontario since 2019 with an obvious outbreak evident in areas of Lambton Shores in 2020.  The result of this outbreak is significant defoliation of targeted trees and a considerable impact on individual enjoyment of outdoor spaces. 

This past summer, the area of Lambton Shores most affected follows the Highway 21 corridor between Port Franks and Grand Bend, including the large forest blocks in the Pinery Provincial Park, the Lambton County Forest and the Ausable Bayfield Conservation Authority.  These areas contain large populations of oak trees.

Frequently Asked Questions

Was there an aerial spray for Gypsy Moths in 2021?

In the spring of 2021, there was a community-led effort to have Zimmer Air Services spray for Gypsy Moths in Lambton Shores. To support those efforts, Council committed to and completed: 

  • Adding a gypsy moth information page to the municipal website
  • Alerting all property owners by mailing out gypsy moth information
  • Waiving any objection to BTK spray
  • Coordinating permissions needed by other levels of government
  • Putting money in the 2021 budget to control gypsy moths on municipal property

On May 31, 2021, Zimmer Air Services Inc. advised the Municipality that their 2021 Aerial Spray Program for the control of Gypsy Moth in Lambton Shores was complete.

Was the 2021 Gypsy Moth aerial spray program organized by the Municipality of Lambton Shores?

The 2021 Aerial Spray Program for the control of European Gypsy Moth was organized by members of the public through private contractors, one of which is Zimmer Air Services Inc. (ZASI). The Municipality participated in the spray program by following the Good Neighbour Approach (information below).

Additionally, the Municipality of Lambton Shores was involved with the issuing of public notices regarding pesticide use, as required by the Ministry of the Environment, Conservation and Parks. Public Notices of Pesticide Use were distributed through several channels, including letters to property owners in the spray areas, newspaper ads, roadside signs, and social media/website messaging.

What does Council’s Good Neighbour Approach mean? 

Council agreed to be a “good neighbour” and will spray its land holdings such as municipal parks and unopened road allowances in support of adjacent property owner initiatives. 

What does this mean?

  • If your property is beside a municipally owned property and you are spraying, the municipality will spray their property beside you
  • If your property is beside a municipally owned property and you object to spray, the municipality will not spray their property beside you

** This is for parks and unopened road allowances.

** Please note that spray coverage will depend on the contractor’s ability to spray the requested area.

What is BTK spray?

Baccillus thuringiensis subspecies kurstaki pesticide (Btk) is a bacterium found naturally in soils. It has been used worldwide as a biological pest control agent to combat a group of insects called lepidopterans (which include the gypsy moth) in forestry and agricultural settings. Btk is also approved for residential and commercial use including aerial application over residential areas.

According to Health Canada, Btk poses little threat to human health either through handling products directly or through indirect exposure such as aerial spraying.

Lambton Public Health has no public health-based objections to aerial spraying of Btk as part of a moth control plan provided that the rules of application as outlined by the Pest Control Products Act and other applicable federal or provincial legislation are strictly followed.

More information about Btk in Lambton Shores.

Will Port Franks Marina be sprayed?

Yes, if possible with the good neighbour approach.  See the “Good Neighbour” drop down above.

Will Port Franks Community Centre property be sprayed?  

Yes, if possible with the good neighbour approach. See the “Good Neighbour” drop down above.

Will Klondyke Park be sprayed?  
There will be control of some sort at the park.  There are not a lot of trees on the property so aerial spray may not be necessary. 

What about road allowance trees?

The municipality owns both "open" and "unopened" road allowances. 

In developed neighbourhoods this "open" road allowance includes the surface you drive on and approximately 15-20’ of land on either side of the roadway.  Road allowance trees are the trees that grow on that 15-20’ that is attached to your yard. 

These trees will get sprayed if you are spraying your property.  This is why the municipality waived objection to overspray.   Zimmer will be able to spray from your lot to the lot across the road without turning his spray on and off every time he crosses the road.

Road allowance trees will not get sprayed if you are not spraying your property.

Unopened road allowances do not have a formal roadway and may still be forested.  If the properties that are adjacent to an unopened road allowance plan to spray, then the Municipality will work with Zimmer to include spraying of the unopened road allowance in keeping with our good neighbour approach.

What can I do to protect my property?

Property owners are responsible for managing trees (and pests) on their property. You are encouraged to monitor trees on your property.  Look for egg masses during the winter, caterpillars in spring, and moths in July and August. There are a number of actions that you can take to control Gypsy Moth at all stages of its life cycle.

The Ausable Bayfield Conservation Authority provides helpful information for controlling the pest throughout its lifecycle in this factsheet: ABCA Factsheet 

Are there other Control Measures to deal with the Gypsy Moth?

The Ausable Bayfield Conservation Authority provides helpful information to homeowners as an alternative (or addition to) aerial spray programs in this factsheet: ABCA factsheet

There are many local landscape and tree companies that also provide various tree health services. This includes tree climbing, pruning and removal, deep root fertilizing, as well as systemic insecticide tree injections and ground based spraying.  Although not an endorsement of any particular service the following list of companies may be considered:

What is the Gypsy Moth lifecycle?  

Gypsy moths spend the winter as partially developed larvae in eggs. The eggs hatch in the spring and the young larvae begin feeding by cutting small holes in the surface of leaves. As the larvae develop, they feed on the edge of leaves. Larvae have five pairs of blue and six pairs of red spots along their backs. Feeding is normally completed by early to mid-July.

Emerged Caterpillars Ausable Bayfield Conservation Authority (2020) - Click to enlarge the image   Gypsy Moth Larvae - Forest Health Monitoring Program, MNRF (2019) - Click to enlarge the image   European Gypsy Moth Male (brown) and Female (white) - City of Toronto - click to enlarge

Pupation occurs in a cocoon which can be found on a variety of surfaces including trees, rocks, houses, boats, trailers, fences, picnic tables, and firewood. In 13 to 17 days, the moths emerge. Both sexes have wings, but only the males can fly. The male moth is dark brown to beige, medium-sized, and is a very erratic flyer. The female is mostly white and has a wingspan between 60 to 70 mm. The female lays eggs in masses of 100 to 1000 on tree trunks, branches, houses, fences, etc. as well as under rocks and forest floor debris. The eggs are covered with fine brown hairs from the female’s abdomen. The egg masses will remain all winter and caterpillars will hatch in the spring, from late April to mid-May.

What kinds of trees are most affected by the Gypsy Moth caterpillar?  

According to the Ausable Bayfield Conservation Authority, Oak, Aspen, Birch and Basswood are the tree species in our area that are preferred by the Gypsy Moth. However, depending on a variety of conditions, including high populations, the Gypsy Moth will eat whichever tree species is available. 

How much damage can Gypsy Moths cause trees? 

Tree damage depends on a number of factors including:

  • The degree of infestation
  • Past defoliations
  • The tree’s vulnerability, and
  • The environment.

Damage to the tree can range from light, to almost complete defoliation. Death to a tree occurs in cases where a tree has been weakened or stressed by other conditions, and defoliated repeatedly in successive years.

Many attacked trees see regrowth of leaves later in the season.

Does the Gypsy Moth have any natural enemies?

Yes. Predators include other insects like wasps, flies, beetles, ants and spiders as well as birds such as chickadees, blue jays, robins and nuthatches. Animals such as chipmunks, squirrels and raccoons will also prey on the caterpillar.

The wasp that targets the gypsy moth is a parasite of the gypsy moth egg. It is now commonly found where ever gypsy moth is and has become an important natural control of the gypsy moth.

Also, the gypsy moth is susceptible to several naturally occurring diseases caused by bacteria, fungi and a virus. The virus and bacteria escalate when gypsy moth populations peak. The gypsy moth virus disease is often referred to as “wilt” because dead caterpillars hang in an inverted “V” from tree trunks or foliage.

These natural biological controls contribute the most to keeping levels within a normal range and tend to become more prevalent as the gypsy moth populations peak.

Additional Links

The links below provide additional information about the Gypsy Moth caterpillar.

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