Notice of Pesticide Use
York Region West Nile virus Mosquito Control Program
From May 1 to October 1, 2026, The Regional Municipality of York in conjunction with the York Region District School Board and York Catholic District School Board will be conducting a larvicide program under the authority of the Medical Officer of Health. The purpose of the program is to control larval mosquitoes to prevent their development into carriers of West Nile virus.
Larviciding is a low risk and effective measure for the control of West Nile virus when used in accordance with label directions. The slow-release pellet formulation interferes with the mosquito life cycle, preventing the mosquito larvae from reaching maturity. It is not sprayed. The products have been approved by both the provincial and federal governments and are considered low risk for humans, pets and the environment.
The pellet formulation of the larvicide methoprene (product name Altosid) with Registration No. 21809, Altosid XR briquets (methoprene) with Registration No. 27694 or Bacillus sphaericus (product name VectoLex WSP) with Registration No. 28009 under the Pest Control Products Act will be placed into catch basins along Regional and Municipal roads and in catch basins on private property, as required.
In addition, the biological larvicide Bacillus thuringiensis subspecies israelensis (product name Vectobac) with Registration No. 18158 or VectoLex CG Registration No. 28008 under the Pest Control Products Act may be placed in ditches and temporary or permanent pools, including storm water retention ponds, if evidence of mosquito breeding is found.
All larvicide will be applied by Ministry of the Environment, Conservation and Parks licensed applicators or trained technicians.
For locations and dates of larvicide treatment contact:
York Region and local municipal properties
- York Region Health Connection at 1-800-361-5653, dial 711 with a TTY device or email @email
York Region District School Board properties
- 1-800-268-1660 or visit the YRDSB Health and Safety Issues page
York Catholic District School Board properties
- 1-800-363-2711 or visit the YCDSB website
For more information on how you can protect yourself and your family from West Nile virus, contact York Region Health Connection at 1-800-361-5653, dial 711 with a TTY device or visit york.ca/WestNile
