• Fall Cankerworm & Gypsy Moth Program 2017

    Mid-May, Forestry staff will be hand delivering the attached notice (“Cankerworm 2017 GroundSpray FINAL” and “GypsyMoth treebanding1”)  to residents in Ward 2 regarding a ground spray program they are conducting to control fall cankerworm.  This insect pest population is increasing in certain areas of the City, particularly the Whiteoaks neighbourhood.  Staff conducted an open house recently weeks to relay this information to residents on the upcoming plans for fall cankerworm, as well as gypsy moth. 



    Fall Cankerworm and City Work Planned in 2017:


    Based on monitoring done in 2016 by the City’s Forestry team, fall cankerworm appears to be on a population rise in certain areas of the City.  As a result, the City will be conducting a ground spray program on City-owned oak trees in impacted neighbourhoods.  Additional control measures will be implemented in parks and woodlots where ground spray would not be effective. The areas of higher cankerworm population correspond to areas that have gypsy moth populations as well.  Bacillus thuringiensis subspecies kurstaki (Btk) will be used in the ground spray program to treat for cankerworm in Mississauga.  Btk is also effective against gypsy moth so we anticipate an impact to both populations of these insects this year in the key neighbourhoods identified (see attached “Streets to Groundspray”).  We will continue monitoring in these neighbourhoods in 2017 and will look at other areas of the City where cankerworm was present but not at higher levels as well.    


    Through a competitive bid process, we have awarded the contract to Greenlawn Ltd (TruGreen).  The City would be unable to negotiate a price for private tree treatment based on the City’s contract with the successful company.  Residents would be required to discuss with neighbours and negotiate with the company on a price that is suitable to them.  The work would not be able to be completed concurrently with the City’s contract as this would be in conflict with City’s contract requirements with the successful company.  The company may be required to return a second day to complete the work for privately-owned trees.


    Gypsy Moth and Toronto’s Aerial Spray Program in 2017:


    City of Mississauga staff have been implementing control measures for gypsy moth since the outbreak in 2006 and 2007.  As part of those measures, staff monitor egg masses every fall/winter and work with a consultant to predict populations for the following year.  Based on these models, staff make management decisions to ensure that gypsy moth populations remain at an acceptable threshold that would not impact the urban forest canopy.  This is done through other control measures such as burlapping, banding with Tanglefoot, egg mass scraping and adult pheromone traps.  These methods are implemented year after year and the City of Mississauga has seen great success with the program and with engaging residents to do the same on their properties.  This has kept the gypsy moth populations at a low level.  Smaller, isolated hot spots that are identified through the modelling can be addressed on an individual basis (eg. TreeAzin injections for individual trees).   


    As you may be aware, this year the City of Toronto is implementing an aerial spray program to control gypsy moth.  Toronto only implements control measures at outbreak levels and appears to see regular outbreaks on a 5 year cycle. Mississauga is currently at year 10 and numbers are remaining consistently low due to the hard work and dedication of City staff and residents in implementing measures year after year.  The insect will never be fully eradicated and implementing yearly control measures will ensure that the insect is kept at acceptable thresholds without heavy reliance on an expensive aerial spray program to control the populations.


    Based on data collected in 2006, when we first implemented an aerial spray program, and our current data from 2016, we are not at the outbreak levels seen 10 years ago when an aerial spray program was required.   


    Gypsy Moth Egg Masses 2006 2016
    Average throughout the City of Mississauga 37/tree 6.9/tree
    Street Trees Only N/A 16.6
    Street Trees After Scraping off Lower Egg Masses (<3m)* N/A 5.8 (egg masses >3m)
    Park Trees Only N/A 2.6
    Maximum Number of Egg Masses on a Single Tree 3250 350

    *One measure that City staff implement throughout the season is to scrape egg masses off trees that are reachable (less then 3m).  Each egg mass can contain 500-1000 caterpillars.  This simple, yet effective, measure can greatly reduce caterpillar populations. 



    Streets to Groundspray