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​Pests & Diseases

Urban forestry preventative maintenance programs include pest preparedness measures to ensure that the City of Barrie’s trees are safe and healthy.

Motion re 2022 LDD Moth* Prevention

City Council has passed a motion that "staff in the Operations Department investigate the feasibility of aerial spraying or the use of pheromone traps for the prevention of gypsy moths, including regional border greenspaces, the costs and report back as part of the 2022 Business Plan and Budget Process." Watch the full discussion of General Committee.

The 2022 budget is scheduled to be approved in December 2021. Engagement with residents will begin in September.

The City's 2021 LDD Moth Management Approach includes the adoption of one of four measures. Please review tips to protect your trees from LDD moth infestation.

There are several diseases and insects that affect trees. Some trees are more susceptible to certain diseases while other trees might be the preferred host for specific insects. Many of these insect populations are kept under control through natural predators and pathogens.

If populations arise to an infestation the City takes on an Integrated Management Approach. Different management techniques are used to address pest populations starting with the least harmful to the environment.

Invasive Insects in Barrie

Invasive insect species to be on the lookout for in Barrie:

  • Asian Longhorned Beetle: Attacks mainly maple trees, but also poplar, birch, willow and elm.
  • Emerald Ash Borer (EAB): Attacks and kills all species of white, green and red ash trees (Fraxinus). Poses a major economic and environmental threat to urban and forested areas.
  • LDD Moth*: Feed on tree leaves, destroying tree growth and taking away trees' ability to produce new leaves. Prefer oak, birch, aspen, sugar maple, American beech, eastern white pine and Colorado blue spruce trees.

*The City recognizes that the term “gypsy" may be perceived as culturally insensitive. To be more inclusive, we now refer to the insect by its Latin name: Lymantria dispar dispar (LDD) moth.​

Protect your Trees from LDD Moth Infestation

2021 was a significant year for LDD moth infestation in Ontario and staff applied an integrated management approach on City property in specific areas, which will continue into 2022. Steps to protect trees on your property are outlined below and should be continued into 2022.

August–April: Destroy Egg Masses

Scrape egg masses off surfaces into soapy water to destroy them:

  1. Wear gloves and safety glasses for protection.
  2. Place a container below the egg mass.
  3. Use a plastic scraper tool or butter knife to remove the egg mass.
  4. Empty the contents into a bucket of soapy water.
  5. Leave the eggs sitting in the bucket for two days to destroy the eggs.

thumbnail images of egg masses 

Helpful videos to reference:

LDD Moth Egg Mass Removal
Source: The City of Toronto

Finding and Removing LDD Moth Egg Masses
Source: The City of Toronto

How to Remove LDD Moth Egg Masses
Source: The City of London

Mid-May to June: Tape

When the caterpillars are in their first instar (tiny stage) they will dispense in the wind and fall to the ground. Instinctively, they find a tree, crawl up to the canopy and begin feeding. Sticky tape can be applied around the tree trunk to prevent caterpillars from reaching the top of the tree.

  1. Wrap two layers of duct tape around the tree then twist is so that the sticky side of the tape is on the outside. Wrap it several times. It should be at a height of 5 feet from the ground.
  2. Complete step 1 but do it a foot below the first tape wrapping.
  3. If the tape is no longer sticking or full off caterpillars remove tape and reapply.
  4. Remove tape in August to prevent damage on the tree trunk.

Helpful video to reference:

Tree wrapping to mitigate LDD moths
Source: The City of Grand Rapids

June to Mid-July: Place Burlap Bands, Collect Pupae, Leave Dead Caterpillars on Tree

If you taped your tree in the spring, remove the tape to prevent damage to the tree.   

Place Burlap Bands Around Tree Trunk

When the caterpillars are in the large caterpillar stage they will move down the tree during the day to seek shelter then return up the tree to feed at night. Placing burlap bands around the tree trunk provides a resting place for caterpillars which can be removed and killed:   

  1. Wrap a piece of burlap cloth around the tree trunk.
  2. Tie rope around the center of the burlap.
  3. Drape the burlap cloth over the rope. This will create an overhang where the caterpillars can crawl underneath to seek shelter during the day.
  4. Check the trap by lifting the overhanging burlap cloth every afternoon and collect any hiding caterpillars.
  5. Put them into a bucket of soapy water for a few days to destroy them.

Helpful video to reference: LDD Moth Burlap trap for caterpillars (Source: The City of Toronto).

Collect Pupae (Cacoons)

The LDD moth caterpillar morphs into the pupal (cocoon) stage in July. This stage generally lasts 10 to 13 days. To help control next year's population, collect the pupae, put them a pail of soapy water, and leave them in the pail for a few days. Then dispose of the pupae in a sealed garbage bag. 

Leave Dead Caterpillars in Place on Tree

If you notice dead caterpillars on your tree, leave them. Dead caterpillars indicate decline. If you leave them, it will help spread the virus or fungus that kills the caterpillars.

How to protect your trees from LDD moths

Once in the moth stage, there are few control options. The moth stage is short-lived and it's best to focus on the other stages when applying control methods.

Boulevard Tree Health Concerns

If you are concerned about the health of your boulevard tree due to LDD moth infestation, please provide your address to Service Barrie at 705-726-4242 or An inspection workorder will be created to review the health of your tree following this season’s LDD moth outbreak (fall 2021). Note: If your tree is in overall good health, defoliation will only stress your tree, not kill it.

Pest Preparedness

Urban forestry staff are responsible for pest preparedness programs and monitoring on City property. Urban forestry preventative maintenance programs include pest preparedness measures to ensure that the City’s trees are safe and healthy.

Two serious threats to the health of our urban forests have been monitored by staff since 2004: the Emerald Ash Borer (Agrilus planipennis) and the Asian Longhorned Beetle (Anoplophora glabripennis). No natural predators or control agents are known to control the populations of these two insects.

LDD Moth Management Approach

City staff monitor the populations of LDD Moth along with our municipal and provincial partners. Related links: Gypsy Moth (County of Simcoe); Gypsy Moth (Province of Ontario).

We cannot eradicate this moth as it is well established throughout North America. LDD moth outbreaks usually occur every 7–10 years and may last for a period of 1–3 years. LDD moth populations naturally collapse from the NPV virus and fungal Entomophaga maimaiga.

2021 will be a significant year for LDD moth infestation in Ontario. Based on a gypsy moth populations assessment from BioForest, there are certain areas in Barrie that will experience moderate to significant levels of defoliation. City staff will be acting in those high infestation areas through an Integrated Pest Management Approach, applying one of four measures outlined below in high infestation areas:

  1. Let nature take care of it: When deciduous trees are healthy, they can withstand a couple of years of defoliation and survive. If the tree health is already in decline or under stress due to other issues (drought, disease, poor soil conditions etc.) die-back or mortality can occur. Although defoliation looks devastating, sometimes it is better to let the LDD Moth population naturally collapse instead of prolonging it with interventions.
  2. Egg mass removal: Scraping egg masses off trees. Egg masses collected and destroyed off site.
  3. Tape banding: Taping trees to prevent caterpillars from reaching the canopy.
  4. TreeAzin injections: Injecting high-risk trees with TreeAzin, a botanical injectable insecticide produced by Neem Tree seed extract that is injected directly into the base of trees. When a caterpillar eats the leaves of a treated tree, the insecticide prevents them from growing any larger. This protects the tree from sustaining significant defoliation.

Forestry staff plan on doing an egg mass survey in winter 2020/21 to determine if we are at the peak of this cycle and to help projected hotspots for next season.

Emerald Ash Borer (EAB) Program

In 2006, City staff instituted a moratorium on planting Ash species on public lands in Barrie and recommended that land developers and consultants omit ash from planting on private property. As of April 1 2014, the County of Simcoe (including Barrie) has been included in the zone under regulation for EAB. Signs and symptoms of EAB-infested ash trees:

  • premature yellowing of leaves
  • dead branches
  • thinning crown
  • branches sprouting from the base of the tree
  • bark cracks
  • a “zig-zag” path under dead portions of bark, and
  • D-shaped holes from where new adults exit the tree.

If a City tree exhibits these signs please report to Service Barrie at 705-726-4242 or If you're concerned that your private tree is infested, staff suggest calling a certified arborist to have it inspected. There are several local tree companies with certified, licensed and insured arborists who can assess your trees and provide recommendations on the best course of action.

Phase 1: 2012 until EAB is discovered in Barrie

a) Identify specimen ash trees for treatment

b) Begin systematic removal and replacement of young ash trees on boulevards

c) Proactive planting in areas of high ash component

d) Public education on EAB

Phase 2: Post Discovery of EAB in Barrie

e) Begin bi-annual treatment of specimen ash

f) Systematic removals to include mature ash where integration with other programs create efficiencies (e.g. block pruning program)

g) Removal of all ash trees on a street or within a park where EAB has been discovered.

On March 26, 2012, after review of Staff Report re Pest Preparedness, Council adopted the EAB Program, a 2-phase project expected to last 15 years. In August 2014, EAB was confirmed within several locations in Barrie. As a result, forestry staff commenced Phase 2 of the EAB Program.

Asian Longhorned Beetle (ALHB) Monitoring

ALHB is native to China and is considered a major pest of hardwood trees in many parts of the country. Based on the Chinese experience with this insect and the infestations in the United States and Vaughan, this beetle would survive and reproduce in the hardwood forests of southern Canada.

A variety of hardwood trees serve as hosts to ALHB. In Asia, the primary hosts are maple (Acer), poplar (Populus) and willow (Salix). Other hosts include; horse chestnut (Aesculus), birch (Betula), elm (Ulmus), sweet-gum (Liquidambar), ash (Fraxinus), mountain ash (Sorbus), mulberry (Morus), plum (Prunus), pear (Pyrus), black locust (Robinia), silk tree (Albizia), hackberry (Celtis), and sycamore (Platanus). All of these genera represent over 1,000 vulnerable species; the first five genera have been found to support reproducing populations in New York and Vaughan.

The ALHB infestation is considered “under control” within the Vaughan/Toronto Regulated Area, and the CFIA are monitoring the area for any further signs of its presence. However, ALHB was found in Mississauga in September 2013, prompting the CFIA to begin the process of starting an eradication program for that population. City staff continue to monitor the CFIA information provided on this pest.

Reporting Pests & Diseases

It is critical to properly identify new introductions and be on the lookout for invasive species before they get established. The spread of pests and diseases cause harm to the ecosystem, economy, society, and potentially human health. If you think that you have spotted an invasive species on City property, please send photos and report location details to Service Barrie at If it's found on your own property please report on EDDMaps Ontario.

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