In the spring, Winnipeg usually receives large amounts of rain that revives the prairie landscape from its dormant state. Unfortunately, this rain and the winter snow-melt result in large amounts of standing water - setting the stage for a potential mosquito infestation. Winnipeg has 39 different mosquito species. Each species has its own preferred host(s).
What do mosquitoes look like?
Adult mosquitoes are a member of the biting fly order (Culicidae). They are called biting flies because they need blood to produce eggs. Mosquitoes have a long thin mouth part called a proboscis with which they obtain a blood meal. Only the female mosquito needs blood for the development of the eggs. You can determine the females by looking at the antennae. Males have very fuzzy antennae and only feed on plant nectar while the females’ antennae have only a few hairs.
Depending on mosquito species, eggs can be laid on the surface or along the edges of water bodies and, depending on the species, can survive up to seven years. They can be laid singularly or in rafts consisting of 50 to 250 eggs each.
Larvae are the immature stage of the adult mosquito. Larvae are often called "wrigglers". They occur in all kinds and types of standing water such as ditches, woodland pools, and unkempt birdbaths. The larvae are filter feeders and mainly ingest algae and organic material to assist in their development. The larval stage has four distinct instars or stages of growth. This is the stage in which the City of Winnipeg focuses its control.
The pupae pictured here are the third stage in the development of the
mosquito. The pupal stage is a tissue reorganization phase where no
feeding occurs. This life stage is also known as a "tumbler".
It may take several days for the pupa to transform into a fully developed
winged adult. When development is complete, the pupal skin splits and the
adult mosquito emerges.
Mosquitoes have a four-stage life cycle: egg, larva, pupa and adult. Only female mosquitoes need a blood meal, which they require to develop their eggs. The males, as well as females feed on nectar for their food source. During its life, a mosquito may take two or three blood meals and develop several hundred eggs each time. Most mosquitoes live four to eight weeks depending on environmental conditions. All female mosquitoes lay eggs in or around water. After being flooded with water, the eggs hatch into larvae and take about seven days depending on temperature to develop into adults. At the water surface, the larva changes to a pupa before emerging as an adult mosquito.
Many of the mosquito problems in your neighbourhood are a result of water-filled containers that you have sitting in your yard. The water in these items can be easily eliminated or can be maintained to prevent mosquito larval development.
You can control mosquitoes around your home and neighbourhood by eliminating standing water. Several hundred mosquitoes can develop in a small amount of water. You can stop mosquito larval development by emptying, turning over or removing anything that can hold water for a week or longer.
Removing standing water is always your most permanent and effective means in reducing mosquito larval development. However in some situations where large standing bodies of water cannot be removed because of size or is an integral part of the ecosystem (marsh), and/or a pump isn't feasible there are domestic larvicides available called Aquabac® 200G and Mosquito Dunks®. All are sold at many home and garden centres. Aquabac® 200G and Mosquito Dunks® contain Bti (Bacillus thuriengensis var. israelensis), which is a biological insecticide that is specific to mosquito larva, and only effective at the larval stage of development. All Pest Control products purchased and used must be registered with Health Canada and contain a Pest Control Product (P.C.P. or PCP) Number on their label.
These are some suggestions that you can easily do to eliminate larval
development in your yard:
Fill in low lying areas where water accumulates
Store inside, turn over or empty containers that hold water
Store children’s toys inside when not in use
Clean and change bird baths weekly
Install a circulating pump or add fish (goldfish, fat head minnows)
to your ornamental pond
Empty water from potted plant saucers
Cover rain barrels with tight fitting screens or add 1 cup of
bleach to a full barrel of water
Keep eaves troughs free of debris
Ensure drains are functioning properly on flat roofs
Remove old tires or store indoors
Clean and remove accumulated water from pool covers
There are many things you can do to protect yourself against mosquitoes:
Make sure all doors and windows fit properly and have tight-fitting, fine mesh screens.
Wear long sleeved shirts and long pants that are light coloured and loose fitting.
Apply an insect repellent that contains DEET. (DEET is not recommended for children under
the age of 6 months.) For more information, go the Manitoba Health web site.
Reduce outdoor activity where mosquitoes are abundant and active. This will be in heavily
vegetated areas and on days that are calm and humid, particularly near sunrise and sunset.
Cover baby carriages and strollers with fine mesh netting to protect infants.
What is West Nile Virus?
West Nile Virus (WNv) is a relatively new disease in Manitoba. The virus is transmitted by mosquitoes. Most people who are bitten by an infected mosquito do not become ill and for those who do, the symptoms are mild. In some cases the virus causes serious illness and sometimes death. More information can be found at Manitoba Health's WNv page.