Fogging is the application of an insecticide to an area to reduce adult mosquito populations. It involves "cold" or ultra-low volume (ULV) foggers. The careful calibration of the insecticide flow-rate on the ULV foggers, plus droplet size analysis helps to ensure accurate application rates and optimum droplet size for controlling adult mosquitoes. All City of Winnipeg ULV units have Global Positioning Systems (GPS), spray-on or spray-off data collection capabilities and moving maps to ensure that when nuisance adult control is warranted all requested buffer zones are respected.
The Insect Control (ICB) will conduct a fogging program as a last resort to control mosquitoes. The ICB has an extensive larviciding program that expands to 12 kilometers outside the City of Winnipeg limits. Larviciding offers the best chance to control mosquito populations because their numbers are more concentrated when in standing water. The ICB’s larviciding program is 100% biological and uses truck-mounted sprayers, backpacks and helicopters to apply larvicide.
Depending on rainfall and weather conditions, the adult mosquito population may rise to a threshold that warrants a fogging program. The ICB uses the New Jersey Light Trap (NJLT) to capture and count adult mosquito numbers. The NJLT counts are only one component in the Adulticiding Factor Analysis (AFA), which the ICB uses to implement an Adult Mosquito Control Policy. In addition to the current adult population, the AFA takes into account a variety of factors that influence adult mosquito populations, including rainfall, temperature, life-cycle stage of the mosquito larva and soil moisture.
If the ICB determines that a fogging program is necessary, they will make announcements through the local media as well as our News Release webpage. The ICB will post regular updates on all of our programs on our News page. Citizens can also register for email and/or telephone notification for a variety of ICB programs.
In addition, citizens can find a map and a list of what parts of the City are being fogged by visiting our fogging schedule page. The ICB notifies what areas are receiving treatment through the use of Insect Management Areas (IMAs). The ICB used Winnipeg's 230+ neighborhood boundaries to create 51 IMAs. Fogging announcements will list the IMAs that are to be fogged. Homeowners can find their IMA, and other address information, by visiting the City of Winnipeg’s Citizen Information Service.
Concerned citizens who do not want their property exposed to the mosquito insecticide can register for a buffer zone. Buffer zone sizes are based on the dispersion distance of the fog and are designed to eliminate the fog that may drift onto a citizen’s property. Buffer zone sizes are determined by Manitoba Conservation and Climate and are a requirement for the Insect Control's Pesticide Use Permit.
The ICB’s fogging program uses truck mounted foggers, computers and Global Position Satellites (GPS) to view buffer zones and record fogging data. When a truck approaches a buffer zone the operator will receive an alarm and turn off the fogging equipment. Fogging trucks typically drive between 15 and 20 km/hr and will have a rooftop beacon and flashing hazard lights. The fogging equipment will sound similar to a lawnmower and produce a slightly visible mist directly behind and above the truck. If conditions are favorable the ICB can fog the entire City in 3 to 4 nights.
Scheduling fogging operations during the dusk-to-dawn period helps to achieve maximum effectiveness because this is when the adult mosquitoes are most active. Fogging starts at sunset, when mosquitoes become most active, and ends at dawn, when activity usually falls off markedly. The hours of operation are usually 9:30 p.m. to 6:30 a.m. and will be conducted if the weather permits. High winds and/or rainfall will reduce the effectiveness of a fogging program and operations will be postponed.
Fogging is conducted using those insecticides that are registered by the Pest Management Regulatory Agency (PMRA). The City of Winnipeg will use DeltaGard® 20EW for large scale adult mosquito control programs beginning this year, if fogging is required. Health Canada's Pest Management Regulatory Agency approved the full registration of DeltaGard® 20EW on May 19, 2017.