LDD moth aerial spraying to begin May 15
The City of Hamilton will begin conducting aerial spraying for Lymantria dispar dispar (LDD) moths - formerly known as gypsy moths - next month in east and west Hamilton, Ancaster, Dundas and Waterdown.
According to a map on the City of Hamilton website, the spraying will take place on five parcels throughout the city.
Robyn Pollard, the city's manager of forestry and horticulture, said in an email Joe Sams Leisure Park in Ward 15 is the only area in Flamborough where aerial spraying will be conducted.
"Joe Sams is the only location included in the aerial sprays within the Flamborough area," she said. "However, staff have conducted egg mass scraping and will be conducting ground spraying for several areas that warranted control, but did not meet the criteria for aerial applications."
The spraying, which will see an organic biological insecticide applied to city-owned wooded properties and residential streets, will help manage the infestation.
It will take place between May 15 and June 15 - although the exact dates and times for the aerial spraying are weather dependent. Each treatment area will be sprayed twice, with the second application occurring 7-10 after the first.
The city has previously said that only city-owned properties would be included in the aerial spraying - with some overspray on private property, but Pollard said that was not necessarily the case.
"Areas within the aerial application were selected to reduce populations of LDD on city-owned lands to reduce the effect on municipal trees. However, private lands will be included due to the nature of utilizing a helicopter to spray large land areas," she explained. "The helicopter is not able to selectively spray street trees only, so in urban areas of Ancaster and Dundas, private property will be included."
In a press release announcing the spraying, the city said the organic biological insecticide that will be sprayed "specifically targets LDD caterpillars and contains a naturally occurring bacterium that when ingested kills the caterpillar within one to two days."
The product, the city said, has minimal environmental impact and will have no health impact on humans, other types of insects, pets, other animals or bees.
City forestry crews have been monitoring LDD moth populations in recent years, and in the fall of 2021 contractors completed egg mass surveys which showed 47 per cent of plots exceeded 2,500 egg masses per hectare - one of the factors used to determine spray locations.
"All areas were determined based on monitoring of the pest," said Pollard. "Where the land mass was significant, the decision was made to utilize helicopters rather than ground spraying to increase the efficacy of control."
The city said that while the aerial spraying program will reduce LDD moth populations in Hamilton, it will not eradicate them entirely. The city will continue public education efforts to inform residents about how they can limit infestations on their own property.
The LDD moth is an invasive pest that was accidentally introduced to the United States from Europe in 1869 and has since expanded its range over much of the eastern United States and Canada. It was first detected in Ontario in 1969 and is now well-established in the south of the province.
The LDD larvae or caterpillars will feed on tree leaves and if the larvae population is too high, can defoliate entire tree canopies and forests in a short period of time. Repeated defoliation of three years or more has the potential to kill trees and cause long-term negative impacts to the urban forest.
In 2008, Hamilton council approved a bylaw to implement control programs if LDD moth populations are above the 2,500 egg mass per hectare threshold. A similar aerial spray program to this year was conducted in 2019.
The city will share up to date details about the spraying 48 hours prior to each application on Twitter at @cityofhamilton and online at www.hamilton.ca/LDDMoth. Residents can use the interactive map on the website to search spray locations by address.