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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.

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.
  • Gypsy 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. 

Protect your Trees from Gypsy Moth Infestation

It's expected that 2021 will be a significant year for gypsy moth infestation in Ontario. Steps to protect trees on your property are outlined below. Related video: How to protect your trees from Gypsy Moths.

September–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.

Helpful videos to reference:

Gypsy Moth Egg Mass Removal
Source: The City of Toronto

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

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

May–July: 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 gypsy moths
Source: The City of Grand Rapids

July & August: Place Burlap Banding Around the 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:

Gypsy Moth Burlap trap for caterpillars
Source: The City of Toronto

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.

Gypsy Moth Management Approach

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

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

It's expected that 2021 will be a significant year for gypsy 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. The City 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 Gypsy Moth population naturally collapse instead of prolonging it with interventions. 
  2. Egg mass removal:  City staff will be scraping egg masses off trees. Egg masses will be collected and destroyed off site. 
  3. Tape banding:  City staff will be taping trees to prevent caterpillars from reaching the canopy.
  4. TreeAzin injections: High-risk trees will be injected 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. 
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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