Mosquitoes spend their early life stages, either as larvae or pupae, in a range of aquatic environments, and usually thrive in warm, nutrient rich, predator-free, stagnant waters, such as:
- shallow floodwater pools
- ephemeral swamps and marshes
- roadside ditches
- ornamental ponds
- rain-fill tires
- horse troughs
Once they emerge as adults, the female mosquitoes search for a blood meal to provide enough protein to produce eggs, from a variety of sources such as amphibians, birds and mammals. Of the 52 species of mosquito known to occur in BC, about 40 are known to bite humans; however, humans may not be the primary source of blood for a majority of species.
Nuisance Mosquito Control Program
Surrey's Nuisance Mosquito Control Program has been in place for many years. The program is managed by Metro Vancouver on behalf of five member municipalities:
- City of Surrey
- Township of Langley
- Maple Ridge
- Pitt Meadows
The goal of the program is to regulate mosquito populations to tolerable levels using environmentally friendly integrated pest management techniques to reduce nuisance mosquito populations. Our program targets primarily the control of floodwater mosquitoes that can emerge in very large numbers in the spring and early summer, usually following the spring freshet caused by snow melting in the mountains, which can lead to extreme annoyance to residents, businesses and vistors.
Mosquito habitat may be identified through targeted routine monitoring and responses to citizen concerns. Monitoring occurs during the mosquito season (generally May through September). This involves strategic sampling of wetted areas suspected to be occupied by mosquito larvae. Monitoring of the identified areas is performed regularly throughout the season by qualified contractor mosquito technicians.
Control of Mosquito Larvae
If predetermined threshold numbers of larvae are exceeded, population management may be conducted using bacterial Bacillus larvicides. The larvicide toxins released by these Bacillus bacteria are highly specific, and will not affect humans, pets, birds, fish and other non-target organisms and provide long term residual control of mosquito larvae. Larvicides are regulated in Canada and the products are used according to provisions of the product label.
The larvicides used are VectoBac® and Vectolex®.
- VectoBac® is a larvicide that kills mosquitoes during the aquatic larval stages of their development. It contains a naturally occurring bacterium, Bacillus thuringiensis israelensis (Bti), which is common in soils in Canada, North America and throughout the world. Bti has been used since the 1950s for insect control and has been thoroughly tested for effects on non-target organisms.
- VectoLex® contains Bacillus sphaericus, and performs in a similar way to Bti but has a slightly longer residual effect and is designed for use in highly nutrient rich waters.
The mosquito control contractor for the Nuisance Mosquito Control Program is
Culex Environmental Ltd. takes calls from residents within the 5 member municipalities on their Mosquito Hotline at 604-872-1912. Call the Mosquito Hotline to report areas of potential concern regarding mosquitoes and to get more specific information about the Nuisance Mosquito Control Program.
West Nile Virus
West Nile virus (WNv) is a mosquito-borne disease that cycles between mosquitoes and birds and can infect people and other animals through mosquito bites. Through biting different animal hosts, a few species are capable of transmitting certain diseases and parasites to which mammals, including humans, are potentially susceptible. Of the forty or so species known to bite humans, the relative risk of transmission of WNv is high in seven species, moderate in four and low in six. The remaining twenty-three species are not competant WNv vectors and are classified as nil risk.
The majority of people infected with WNv will experience only mild symptoms which may go completely unnoticed. Around 20 percent will however develop mild flu-like symptoms lasting a week or less. Symptoms typically include:
- head and body aches
- sometimes swollen lymph glands
In less than 1 percent of cases, the virus can cause more serious conditions such as meningitis (inflammation of the lining of the brain and spinal cord) or encephalitis (inflammation of the brain), which can be fatal.
In areas where the virus is present, very few mosquitoes, much less than 1 percent, may become infected. If bitten by an infected mosquito, generally less than 1 percent of people will become infected and only a fraction of those will become severely ill. People over 50 years of age are most at risk for severe illness. The risk of becoming seriously ill from the virus is thus very low, but precautions should nonetheless be taken to avoid mosquito bites and reduce mosquito breeding areas. Being aware of the threat of WNv and the need to protect yourself from mosquito bites goes a long way to reducing the chances of becoming infected.
Due to the lack of any serious outbreaks of WNv in the Lower Mainland and Fraser Valley, and following directives from the BC Centre foir Disease Control and Fraser Health Authority in 2012, municipalities are no longer conducting WNv risk reduction programs.
Zika virus was first identified in 1947 as a result of a study into Yellow Fever that was being carried out in the Zika Forest in Uganda and first human infection was not discovered until 1952. Between 1951 and 1983 it spread slowly but steadily from Africa to Asia, and then onto Micronesia until finally reaching the Americas and the Pacific in 2015. It appears to have arrived in Brazil in May 2015 and the first documented human case was on February 1, 2016. Within months, the World Health Organization (WHO) declared a Public Health Emergency of International Concern. It is very unlikely to become a major concern in Western Canada as the two known mosquito species vectors of Zika virus, Aedes aegypti and Aedes albopictus, are not found here. Warming temperatures may allow these mosquito species to spread further north from their current range within the southern United States but this could take years. Zika virus symptoms are usually mild, with only 1 in 5 infected people becoming ill. Symptoms may include:
- skin rash
- conjunctivitis (red eyes)
- joint pain
For more information about health related concerns around Zika virus please see the following links:
- Center for Disease Control and Prevention
- World Health Organization
- Fraser Health
- BC Center for Disease Control
You can also speak to a health-care professional any time of day or night by dialing 8-1-1.
What you can do
Reduce the Risk of Mosquito Bites
The best protection is to avoid mosquito bites and reduce mosquito populations in your home and yard. We recommend:
- Use insect repellent when outdoors either containing DEET (10% for children and up to 30% for adults) or any product containing Picaridin – always follow the manufacturers recommendations on the label
- Avoid mosquito-laden areas during dawn and dusk
- Wear loose, light coloured clothing when outdoors, including long-sleeved shirts and pants
- Apply tight-fitting, well maintained screens to doors and windows
- Keep your lawn regularly mowed to decrease mosquito rest areas
- Eliminate or regularly changing any sources of stagnant water around your home such as saucers under flower pots, bird baths, wading pools, boat tarpaulins, and other areas where rainwater may collect
Prevent Mosquito Breeding
In order to prevent mosquito breeding, we recommend these tips:
- Dispose of tin cans, old tires, buckets, plastic sheeting, or other containers that collect and hold water
- Clean bird baths regularly
- Repair leaky plumbing and outside faucets
- Clean out leaves and other debris blocking and holding water in roof gutters
- Empty your pets' water dishes daily
- Water lawns and gardens carefully to prevent water from standing for several days
- Empty or cover swimming and wading pools when not in use
For more information regarding Surrey's Nuisance Mosquito Control Program, contactor Nuisance Mosquito Control Hotline 604-872-1912.