Mosquitoes and Midges

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Why do mosquitoes feed on humans?

Only adult female mosquitoes require a blood meal (protein) to produce eggs. Mosquitoes are attracted to carbon dioxide (exhaled air), warmth, body odour, perspiration and light.

Does the City spray lakes or man-made water bodies and structures?

No. The City's lake systems are of significant environmental importance. The City does not chemically treat any of the natural lakes or wetlands in Cockburn for mosquitoes. The Public Health Services team treat mosquito breeding in man-made water bodies with environmentally sensitive treatment options. The City focuses on residential swimming pools that have not been maintained through filtration and chlorination, as they can provide breeding grounds for mosquitoes. The City uses data from the Nearmaps system, which is updated monthly, to identify unmaintained pools.

What can I do to protect myself and my home?

• Reduce outdoor activities during dawn and dusk  
• Cover up by wearing light coloured long sleeve shirts and long pants that are loose fitting
• Apply personal insect repellent containing DEET or Picaridin if possible
• Ensure fly screens to doors and windows are fitted and maintained

Check your property for potential breeding sources:

• Empty pot plant bases weekly or fill the base with sand to absorb water
• Bromeliads and other water holding plants should be washed out weekly
• Clean roof gutters out regularly and trim back trees which can block gutters
• Ensure rainwater tank overflow pipes are screened and access covers fitted securely
• Keep swimming pools maintained
• Ensure plumbing and vents to septic tanks are screened
• Wash out birdbaths and ornamental pools weekly.

Frequently Asked Questions

Does the City monitor for mosquitos? 

The City’s Health Service may from time to time trap mosquitoes for monitoring purposes using dry ice (carbon dioxide) and light traps. Some of the locations may include Manning Park, Market Garden Swamp, Kevin Bowman Reserve Munster, L'aquila Park, Beeliar & Success Regional Sport & Community Facility.  Health Services also respond to enquiries and requests regarding increased mosquito numbers in residential areas. 

What diseases do mosquitos transmit? 

Although most mosquitoes will be considered a nuisance, entering houses and buzzing in your ear whilst searching for a blood meal, some species are known spreaders of Ross River Virus (RRV) and Barmah Forest Virus (BFV).  RRV and BFV can impact significantly on an infected person’s lifestyle – symptoms can include painful and/or swollen joints, sore muscles, aching tendons, skin rashes, fever, tiredness, headaches and swollen lymph nodes. It is Health Services aim to reduce annual reported cases of RRV and BFV within the City by introducing sound management principles and practices.

Why do mosquitoes need a blood meal? 

It is only the adult female mosquito that requires a blood meal (protein) to produce eggs. Some mosquito species can fly up to 50km in search of a blood meal, most species average up to 2-5km. Mosquitoes are attracted to carbon dioxide (exhaled air), warmth, body odour, perspiration and light.  

Do Public Health Services spray the lakes? 

The City’s lake systems are not only recreationally and aesthetically valuable but of significant environmental importance. For example Thomsons Lake is a 'Ramsar' listed Wetland of International Importance (migratory birds).

The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of Ramsar sites. It is also known as the Convention on Wetlands. It is named after the city of Ramsar in Iran, where the convention was signed in 1971.

Thomsons Lake is one of 19 wetlands in Beeliar Regional Park and is the largest lake in the regional park’s eastern chain of wetlands. Collectively the lakes form one of the most important wetland systems in the Perth metropolitan area. For  this reason the City’s Health Service does not chemically treat any of the natural lakes and ecosystems.

What about man made water bodies and structures? 

Health Services are actively investigating, mapping and where necessary treating mosquito breeding man made water bodies with target specific and environmentally sensitive treatment options.  City owned infrastructure such as stormwater compensation basins, bubble up sumps, drainage gully’s and similar are the main focus for this upcoming season.  

Health Services also focus on residential swimming pools that have not been maintained and which can provide breeding grounds for mosquitoes.  The City’s mapping system can identify unkempt pools and contact can be made to property owners requesting them to take action to remediate them. 

Midge management

What are midges?

Chironomidae, commonly known as midge, are a large and diverse family of flies. They are commonly known as "non-biting midges." Often confused with mosquitoes, no members of this family are blood-feeders. Adults feed on nectar or similar substances, if they feed at all.
Midge larvae are nearly all aquatic or sub-aquatic, and are a very important part of many freshwater ecosystems.

Why do we monitor midge numbers?

It is important to monitor midge numbers to help predict and minimise the nuisance caused to residents living near wetlands. Nuisance midge problems are often a sign of a more significant problem such as wetland ecosystem degradation. Wetland areas need to be well maintained and preserved to provide wildlife, including invertebrates, with suitable habitats.

Midge management program

The City’s midge monitoring and control program includes:

• Conducting regular monitoring programs of water  and sediment  samples throughout the midge season
• Revegetation programs including the installation  of nutrient stripping basins
• Promotion of waterwise gardens
• Liaising with other management agencies such as  the Water Corporation and the Department of Parks  and Wildlife
• Liaising with experts from tertiary institutions  to further understand and control nuisance midge
• Trialling treatments methods specific to midge
• Implementing a control program in response to  midge larvae numbers and customer complaints
• Installing light traps and developing new and more efficient (environmentally-friendly) methods  for midge control such as the installation of Bat boxes
• Aerial chemical treatment of lakes when warranted
• Maintaining revegetation buffers around wetlands
• Supporting appropriate land use adjacent to wetlands
• Public education
• Continuously reviewing the City’s Integrated Midge Control Strategy.

Long term midge control

Long term options are the most desirable as they address the underlying causes of midge breeding such as nutrient enrichment and the loss of natural vegetation surrounding wetlands. Control measures include:

• The re-establishment of fringing vegetation surrounding wetlands to take up nutrients, shade and cool the water and to screen light from residential areas as midge are attracted to lights
• Preventing nutrients from entering lake systems by reducing fertiliser use around wetlands and encouraging residents to minimise runoff from their own properties
• The introduction of bat boxes to increase bat populations that feed on adult midge.

Improving water quality will lead to conditions which are less favourable to midges, resulting in lower midge numbers in the long term.

Short term midge control

These options only treat the nuisance symptoms and not the underlying cause of excessive midge numbers. Control measures include:

• Use of growth inhibitors specific to midge which prevent larvae from progressing  to the adult stage
• Using light traps for flying adult midges
• Installing bat boxes.

Problems associated with overuse of larvicide and insecticide include the development of resistance and killing of non-target organisms such as natural midge predators.

What can I do to minimise midge problems?

If you are experiencing midge problems, you can take the following actions:

• Keep windows and doors closed
• Install fine mesh insect screens
• Place electrocuting light traps around your property
• Avoid light coloured surfaces around your home - these reflect light and attract midges
• Green and dark blue surfaces are most desirable
• Screen light from the sources of midges
• Reduce the number and wattage of outside lights
• Use yellow external lights or sensor security lights
• Use outdoor foggers (insecticides) when entertaining.

 For more information contact Environmental Services on 08 9411 3444.