2022 Aerial Spray Program

graphic of helicopter, caterpillars and mothsThis spring, the City of Mississauga is conducting an aerial spray to manage high-population levels of LDD (Lymantria dispar dispar) in areas where severe leaf loss is expected from caterpillar feedings.

Subscribe to receive news alerts by email

Check the interactive map to see if your neighbourhood is in the spray zone

Watch a video recording of the virtual public meeting held on April 20

Questions? Email us at public.info@mississauga.ca or call 311 (or 905-615-4311)

Follow @citymississauga and @saugaparksrec on social media


When and where will the spray occur?

The initial spray window was set for April 25 to June 12, 2022; however, updated modelling available to the City has narrowed the spray dates to May 15 to June 12 between 5:00 a.m. and 7:30 a.m.

The spray will treat areas of Mississauga predicted to see severe leaf loss from caterpillar feedings. The area is roughly 2,100 hectares (5,189 acres) of private and public land in Wards 1, 2, 3, 5, 6, 7, 8, 9, 10 and 11.

Highly trained spray specialists contracted by the City will use a helicopter, with all activities monitored by the project team. All necessary safety precautions are taken to ensure minimal risk to the public and the applicators.

Leaf size, caterpillar size and weather conditions will determine exact spray dates. Applications can occur any day of the week, including weekends. Application is weather dependent and the proper wind conditions are needed. Ideal application conditions consist of:

  • calm winds
  • no precipitation within for 24 to 48 hours
  • high humidity

Each area will be sprayed twice, with the applications done approximately 7-10 days apart.

The City will be monitoring conditions during the spray window and will provide confirmation of the spray dates 48 hours in advance. Spray dates can be cancelled if the conditions change.

A communication will be issued by the City to the public 48 hours before each treatment. Up-to-date information will be provided through various communications channels listed in the How can I stay informed? section below.


➡️ View an interactive map of the spray area to see if your neighbourhood is included


Why is an aerial spray necessary?LDD caterpillars eating tree leaves

On February 16, 2022, Council passed a by-law (BL0029-2022) to declare the LDD infestation in Mississauga a matter of public nuisance. The by-law authorizes the Parks, Forestry and Environment division to implement an aerial spray program using Bacillus thuringiensis subspecies kurstaki (Btk) to control LDD within treatment areas identified by the Commissioner of Community Services.

If left unmanaged, elevated populations of LDD will lead to significant defoliation of the City’s tree canopy. This can cause certain trees to become more susceptible to disease and extreme weather events like drought and ice storms.

The most efficient way to treat widespread LDD populations is to apply an organic pesticide from the air. While the aerial spray will not eradicate LDD population levels. It will reduce populations to more manageable level and help protect the City's urban forest.

Low-flying helicopters will target the spray to the tops of trees so that the spray is applied to tree leaves.

After the spray, the City will continue to monitor LDD population levels and treatment methods for effectiveness.


➡️ Learn more about LDD


What is being sprayed and is it safe?helicopter spraying Btk on top of some trees

According to Health Canada, Btk treatment is considered low-risk to human health and the environment. Btk is only toxic in the caterpillar stage of the LDD life cycle and does not affect adult moths or butterflies.

Btk works by producing a protein that is only toxic to caterpillars of specific insect species like LDD. When ingested by an LDD caterpillar, the toxic protein molecules break down the walls of its stomach causing it to stop feeding and die.

The City will be using a product called Foray® 48B Biological Insecticide, Aqueous Suspension, which contains the active ingredient Btk. It is registered under the Pest Control Product Act (registration #24977) and is approved by Health Canada for use in urban areas. This has been used effectively in all past aerial sprays in Mississauga to control for LDD (2006, 2007, 2018).


➡️ View the material safety data sheet for BTK formulation Foray® 48B

➡️ Residents with any concerns or questions about health and the use of Btk can call Peel Public Health at 905-799-7700 or speak to their family doctor.


How do I prepare?

The City is committed to ensuring all possible steps are taken to keep Mississauga healthy and habitable for all residents. The safety and health of residents and the protection of the environment are top priorities. The public may hear helicopter noises during the early morning. All necessary safety precautions are taken to ensure minimal risk to the public, staff and the applicators.

Peel Public Health recommends that residents stay indoors during the spray and for 30 minutes following the spray to allow the droplets to settle.

Before the spray, residents should:

  • close windows
  • turn off fans or air conditioners, or select the recirculate setting
  • bring in laundry and toys
  • cover all vegetable and herb gardens
  • keep pets indoors
  • cover pools, BBQs, play equipment, lawn furniture, and automobiles

After the spray, residents should:

  • wash/rinse pool covers BBQs, play equipment, lawn furniture and automobiles with water
  • Practice good personal and food hygiene (e.g. hand washing after outdoor activities, especially after gardening; leave outdoor shoes at the door; washing all fruits and vegetables before eating or cooking)
  • wash pets’ paws before entering the home


➡️ Residents with any concerns or questions about health and the use of Btk can call Peel Public Health at 905-799-7700 or speak to their family doctor.


How can I stay informed?

In advance of the spray, the City will inform residents of specific areas of the flight path, treatment plan and any other relevant information. Project updates will be posted on this webpage.


➡️ Watch a video recording of the virtual public meeting held on April 20

➡️ Read the answers to some frequently asked questions

➡️ Subscribe to receive news alerts by email

➡️ Follow @citymississauga and @saugaparksrec on social media

➡️ Visit this webpage frequently as project updates will be posted here as more information becomes available.

graphic of helicopter, caterpillars and mothsThis spring, the City of Mississauga is conducting an aerial spray to manage high-population levels of LDD (Lymantria dispar dispar) in areas where severe leaf loss is expected from caterpillar feedings.

Subscribe to receive news alerts by email

Check the interactive map to see if your neighbourhood is in the spray zone

Watch a video recording of the virtual public meeting held on April 20

Questions? Email us at public.info@mississauga.ca or call 311 (or 905-615-4311)

Follow @citymississauga and @saugaparksrec on social media


When and where will the spray occur?

The initial spray window was set for April 25 to June 12, 2022; however, updated modelling available to the City has narrowed the spray dates to May 15 to June 12 between 5:00 a.m. and 7:30 a.m.

The spray will treat areas of Mississauga predicted to see severe leaf loss from caterpillar feedings. The area is roughly 2,100 hectares (5,189 acres) of private and public land in Wards 1, 2, 3, 5, 6, 7, 8, 9, 10 and 11.

Highly trained spray specialists contracted by the City will use a helicopter, with all activities monitored by the project team. All necessary safety precautions are taken to ensure minimal risk to the public and the applicators.

Leaf size, caterpillar size and weather conditions will determine exact spray dates. Applications can occur any day of the week, including weekends. Application is weather dependent and the proper wind conditions are needed. Ideal application conditions consist of:

  • calm winds
  • no precipitation within for 24 to 48 hours
  • high humidity

Each area will be sprayed twice, with the applications done approximately 7-10 days apart.

The City will be monitoring conditions during the spray window and will provide confirmation of the spray dates 48 hours in advance. Spray dates can be cancelled if the conditions change.

A communication will be issued by the City to the public 48 hours before each treatment. Up-to-date information will be provided through various communications channels listed in the How can I stay informed? section below.


➡️ View an interactive map of the spray area to see if your neighbourhood is included


Why is an aerial spray necessary?LDD caterpillars eating tree leaves

On February 16, 2022, Council passed a by-law (BL0029-2022) to declare the LDD infestation in Mississauga a matter of public nuisance. The by-law authorizes the Parks, Forestry and Environment division to implement an aerial spray program using Bacillus thuringiensis subspecies kurstaki (Btk) to control LDD within treatment areas identified by the Commissioner of Community Services.

If left unmanaged, elevated populations of LDD will lead to significant defoliation of the City’s tree canopy. This can cause certain trees to become more susceptible to disease and extreme weather events like drought and ice storms.

The most efficient way to treat widespread LDD populations is to apply an organic pesticide from the air. While the aerial spray will not eradicate LDD population levels. It will reduce populations to more manageable level and help protect the City's urban forest.

Low-flying helicopters will target the spray to the tops of trees so that the spray is applied to tree leaves.

After the spray, the City will continue to monitor LDD population levels and treatment methods for effectiveness.


➡️ Learn more about LDD


What is being sprayed and is it safe?helicopter spraying Btk on top of some trees

According to Health Canada, Btk treatment is considered low-risk to human health and the environment. Btk is only toxic in the caterpillar stage of the LDD life cycle and does not affect adult moths or butterflies.

Btk works by producing a protein that is only toxic to caterpillars of specific insect species like LDD. When ingested by an LDD caterpillar, the toxic protein molecules break down the walls of its stomach causing it to stop feeding and die.

The City will be using a product called Foray® 48B Biological Insecticide, Aqueous Suspension, which contains the active ingredient Btk. It is registered under the Pest Control Product Act (registration #24977) and is approved by Health Canada for use in urban areas. This has been used effectively in all past aerial sprays in Mississauga to control for LDD (2006, 2007, 2018).


➡️ View the material safety data sheet for BTK formulation Foray® 48B

➡️ Residents with any concerns or questions about health and the use of Btk can call Peel Public Health at 905-799-7700 or speak to their family doctor.


How do I prepare?

The City is committed to ensuring all possible steps are taken to keep Mississauga healthy and habitable for all residents. The safety and health of residents and the protection of the environment are top priorities. The public may hear helicopter noises during the early morning. All necessary safety precautions are taken to ensure minimal risk to the public, staff and the applicators.

Peel Public Health recommends that residents stay indoors during the spray and for 30 minutes following the spray to allow the droplets to settle.

Before the spray, residents should:

  • close windows
  • turn off fans or air conditioners, or select the recirculate setting
  • bring in laundry and toys
  • cover all vegetable and herb gardens
  • keep pets indoors
  • cover pools, BBQs, play equipment, lawn furniture, and automobiles

After the spray, residents should:

  • wash/rinse pool covers BBQs, play equipment, lawn furniture and automobiles with water
  • Practice good personal and food hygiene (e.g. hand washing after outdoor activities, especially after gardening; leave outdoor shoes at the door; washing all fruits and vegetables before eating or cooking)
  • wash pets’ paws before entering the home


➡️ Residents with any concerns or questions about health and the use of Btk can call Peel Public Health at 905-799-7700 or speak to their family doctor.


How can I stay informed?

In advance of the spray, the City will inform residents of specific areas of the flight path, treatment plan and any other relevant information. Project updates will be posted on this webpage.


➡️ Watch a video recording of the virtual public meeting held on April 20

➡️ Read the answers to some frequently asked questions

➡️ Subscribe to receive news alerts by email

➡️ Follow @citymississauga and @saugaparksrec on social media

➡️ Visit this webpage frequently as project updates will be posted here as more information becomes available.

Page last updated: 17 May 2022, 09:52 AM