2022 Aerial Spray Program

This 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.

Latest Update

The City of Mississauga completed round two of the Aerial Spray Program on June 8, 2022. This marks the end of the 2022 Aerial Spray Program. Thank you for your patience and co-operation during this time and we appreciate your understanding for any inconvenience the aerial spray logistics may have caused.

City staff will continue to monitor the treatment areas over the season to evaluate the effectiveness of the program.

We encourage those in affected spray zones to monitor trees on their property for signs of LDD (Lymantria dispar dispar). You can help by:

  • Year-round: reporting sightings of LDD through the City's reporting form
  • Now - July: installing burlap skirts around your tree trunks and destroying any caterpillars and pupae
  • August - May: scraping egg masses off of trees and other hard surfaces and soak them in soapy water for at least 48 hours


Learn more about managing LDD on your property.


What is the Aerial Spray? When and where will the spray occur?

This 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.

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 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 Stay Informed section below.


Interactive Map

Check the interactive map to find out if your neighbourhood is in a designated spray zone (view map instructions).


How to 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.

Most residents are unlikely to experience any symptoms if exposed. A small percentage of sensitive residents may experience skin, eye, or respiratory irritation.

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

See more actions you can take.


Top FAQs


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.

This 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.

Latest Update

The City of Mississauga completed round two of the Aerial Spray Program on June 8, 2022. This marks the end of the 2022 Aerial Spray Program. Thank you for your patience and co-operation during this time and we appreciate your understanding for any inconvenience the aerial spray logistics may have caused.

City staff will continue to monitor the treatment areas over the season to evaluate the effectiveness of the program.

We encourage those in affected spray zones to monitor trees on their property for signs of LDD (Lymantria dispar dispar). You can help by:

  • Year-round: reporting sightings of LDD through the City's reporting form
  • Now - July: installing burlap skirts around your tree trunks and destroying any caterpillars and pupae
  • August - May: scraping egg masses off of trees and other hard surfaces and soak them in soapy water for at least 48 hours


Learn more about managing LDD on your property.


What is the Aerial Spray? When and where will the spray occur?

This 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.

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 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 Stay Informed section below.


Interactive Map

Check the interactive map to find out if your neighbourhood is in a designated spray zone (view map instructions).


How to 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.

Most residents are unlikely to experience any symptoms if exposed. A small percentage of sensitive residents may experience skin, eye, or respiratory irritation.

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

See more actions you can take.


Top FAQs


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.

Page last updated: 08 Jun 2022, 09:55 AM