Middlesex Centre has been working to protect trees on municipal property in those areas hardest hit by spongy moth (previous called gypsy moth) infestations.
In the winter of 2021, the municipality brought in third party consultant (Stantec) to conduct a field study to better understand extent of infestation and risk to trees in municipal parks. Considering the extent of the infestation and management options available, in 2021 the municipality conducted aerial spraying of BTK, a commonly used insecticide for spongy moth control in Canada, over woodlots in Kilworth and Ilderton. This year will see aerial spraying in different targeted areas of Kilworth and Ilderton (see map at bottom of page).
BTK (Bacillus thuringiensis var. kurstaki) has been used in Canada for more than 30 years, and is considered safe for humans, animals, fish and non-target insects. It breaks down quickly in the environment. It must be applied when the spongy moth caterpillars are in an early larval stage to be most effective, which is around May 20th in our area. Exact spray timing depends on insect and tree development and is weather dependent.
Notice of Spraying
Properties near the area the spraying will be conducted will receive written information from the municipality. Notice will be provided on the municipal website as well.
Traffic (vehicles and foot traffic) may be limited in certain areas while the spraying takes place.
Spraying will take place by a twin-engine helicopter, with two rounds of spraying occurring a few days apart. The best time to spray is often early in the morning. It is expected that the two treatments will be performed between 5 and 8 a.m. sometime between May 16 and June 15, 2022.
UPDATE: The first of these two treatments took place Tuesday, May 24, 2022. The second took place Tuesday, May 31, 2022.
You can sign-up to receive email notifications about the spraying dates at middlesexcentre.ca/spongymoths.
Frequently Asked Questions
What is spongy moth?
Spongy moth (Lymantria dispar) is an invasive species that is severely weakening trees across North America. Unfortunately, parts of Middlesex Centre are experiencing an infestation of spongy moth.
What happens during an infestation?
Spongy moth outbreaks occur every 7 to 10 years. Spongy moth caterpillars (“larvae”) will chew holes in leaves, and may partially or totally strip a host tree of its leaves.
During outbreak years, nearly all broadleaf (hardwood) trees may be completely defoliated. This can harm and even kill otherwise healthy trees. Caterpillars appear everywhere and their droppings ("frass") will fall from the trees.
This species is known to infest trees in woodland or suburban areas. They prefer to infest hardwood species, such as oak, birch, poplar, willow, maple and others.
Why has Middlesex Centre decided to spray for spongy moths?
A third-party consultant conducted a field study that showed the extent of the infestations in certain areas. After considering the findings of the study and the management options available, aerial spraying was considered the best option.
Can other methods be used to control spongy moth?
There are a number of options to control spongy moth infestations, including banding trees and scrapping off egg masses. While these may be sufficient for smaller infestations, they are not considered adequate given the moderate-to-large infestations the targeted areas are experiencing.
Does spraying impact property use?
There will be a very limited impact on property use for those adjacent to the spray areas. It is important that people are not outside during aerial spraying for safety and regulatory requirements related to low-level flying. (A twin-engine helicopter will be used.) You may also notice a brief, unpleasant odour.
How will I know when spraying will occur?
Advance notice will be provided to affected properties and will be posted on the municipal website and social media channels. You may also sign-up to receive email notifications at middlesexcentre.ca/spongymoths.
What type of pesticide is being used?
The spraying program consists of 2 applications of Foray 48B PCP # 24977 applied a few days apart. The active ingredient in Foray 48B is BTK (Bacillus thuringiensis var. kurstaki), which has been used in Canada for more than 30 years, and is considered safe for humans, animals, fish and non-target insects. It breaks down quickly in the environment after a few days.
How does the pesticide work and is it safe?
When it is ingested by a caterpillar (larvae), the bacteria (BTK) creates a toxic crystalline protein. Btk is not considered a human health risk and it is not toxic to bees and other insects, birds, fish, mammals or adult moths/butterflies. It does not impact moth and butterfly species, like monarchs, whose caterpillars emerge later in the season.
Foray® 48B use is approved by Health Canada including for aerial application over urban areas. (Source: GRCA)
What personal precautions should people be taking related to the aerial spraying?
Spraying is done in low wind conditions to ensure the spray remains within treatment areas, so only those immediately in the spray areas need to take any precautions. Those residents will receive a direct notice.
Those in the spray area should:
Respect the request to stay indoors during the spraying, and stay indoors for a minimum of 30 minutes after the spraying to let the droplets settle.
- Keep pets indoors during the spraying.
- Close windows and doors.
- Cover outdoor tables, furniture, and equipment or wash with water soon after spraying.
- Bring in laundry and toys.
- Close and/or cover BBQs – if left uncovered wash soon after spraying
- Refill kiddy pools, pet water dishes, etc. with fresh water following spraying
What about pets?
Health Canada states that there have been no documented cases of toxicity in mammals over the many years Btk has been in use in Canada. Btk naturally biodegrades quite quickly over one to four days. (Source: GRCA)
Will the spray damage my house or vehicle?
The spray will not damage your house, vehicle or other items. It may leave a film that you can wash off with water. You may want to cover items that you would prefer not to be exposed to the spray.
When will you spray woodlots in my area?
The decision to aerial spray municipal woodlots is based on a number of factors, including infestation rates, risk of damage to trees and woodlot health, and also cost. There are a number of lower-cost alternatives for dealing with smaller infestations.
If you would like to report a municipal property (park, woodlot, etc.) that you feel should be considered in the future, please email Scott Mairs, Director of Community Services.