Mosquitoes and midges

Mosquitoes

Within Australia there are more than 300 different species of mosquito but only a small number cause nuisance biting problems or spread disease-causing pathogens.

Are mosquitoes a health concern?

The two most common mosquito-borne diseases in our local area are Ross River fever and Barmah Forest Virus. These diseases are not fatal but can cause symptoms including joint pain, muscle tiredness, fatigue, fever, and rash that may last from days to months. Mosquitoes within Ballina Shire do not transmit dengue or malaria.

Why do mosquitoes bite?

Only the female mosquito will bite humans. The female mosquito needs the protein in a blood meal to help develop their eggs. Mammals including wallabies, birds, dogs, cats, snakes, and other native wildlife are other blood sources. While taking blood they can pass on disease-causing viruses and parasites. Exposure to large numbers of mosquitoes may increase the chance of being infected with a mosquito-borne disease.

What are Ross River Fever and Barmah Forest virus?

Ross River fever and Barmah Forest virus are infections that are spread to humans through mosquito bites. Mosquitoes are not “born” infected with either virus, they must acquire the viruses from an infected animal. The viruses occur throughout most regions of Australia. Human infections tend to occur more often in regions with a warm, humid climate that are close to bodies of water where mosquitoes breed.

Ross River fever and Barmah Forest virus have the same symptoms including fatigue, rashes and muscle aches and pains. There is no specific treatment; however plenty of rest, moderate exercise and healthy eating may help reduce the recovery time.

Why mosquitoes seem to bite some people more

There are over 400 chemical compounds on human skin that could play a role in attracting mosquitoes.

There's always one in a crowd, a person mosquitoes seem to target more than others. What is it about these unlucky few that make them so attractive to mosquitoes? Or is it the reaction people experience which make them think they are being targeted by mosquitoes? Visit the Conversation website -  why mosquitoes seem to bite some people more 

How to protect yourself

• when outside cover up as much as possible by wearing loose fitting, light coloured clothing and covered footwear
• avoid being outside when mosquitoes are most active, around dusk and dawn
• apply a topical insect repellent - choose any product that contains DEET, picaridin, or oil of lemon eucalyptus. Apply an even coat over all exposed areas of skin and you’ll get the longer lasting protection
• light mosquito coils or use vapour mats indoors. Devices that use light to attract and electrocute insects have been proven to be ineffective in reducing mosquito numbers
• cover all windows, doors, vents and other entrances with insect screens.

Minimise mosquitoes at home

• Install insect screens on all windows and external doors. Check them regularly and mend any holes.
• Keep vegetation in yard well maintained and mow lawns regularly.
• empty out bird baths, pet water bowls, and water features with a hose on a weekly basis
• dispose of pot plant bases, fill with sand or empty and clean the base weekly
• tip out, cover up, or throw away any containers that collect water - mosquitoes love these
• ensure gutters are kept free of leaves and drain freely
• keep swimming pools chlorinated or salted and operate the pool pump all year round
• screen all openings to tanks, wells, and other large water containers
• stock fishponds with native fish that will feed on mosquito eggs and larvae.

What is Council doing?

Although Council does not spray for mosquitoes, Council’s Environmental Health Officers are actively involved in mosquito monitoring during the warmer months and data collected is provided to NSW Health to assist in minimising mosquito borne risk.

The program involves trapping of mosquitoes at a number of sites within the Ballina Shire. The mosquitoes are sent to Westmead Hospital where the species are identified and counted with any arboviruses (Arthropod-borne viruses) isolated from mosquitoes when present. For the results of trapping and further information on the program visit Mosquito-borne disease surveillance - Mosquito borne diseases (nsw.gov.au).

Additionally, Council work with planning consultants, entomologists and landscape architects to ensure new development is designed to minimise the exposure of residents to mosquitoes. Chapter 2 of Council’s Development Control Plan has controls for new developments to help minimise the impacts of mosquitoes. This includes things like:

• placing an open buffer between a mosquito habitat and the development
• ensuring any vegetation, water holding devices, including stormwater infrastructure, do not provide mosquito habitat. 

This issue is also considered at rezoning stage.

Council continues to engage experts to review the provisions in Council’s Development Control Plan so they can be improved to further minimise mosquito impacts. These reviews inform Council of best practice and leading science to minimise nuisance and public health risks associated with mosquitoes.

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Midges

Biting midges, commonly known as sandflies, are small insects that belong to the family of flies Ceratopogonidae. Some species of biting midge are known to suck blood from humans and animals. Biting midges can cause a nuisance in coastal lagoon environments, estuaries, mangrove swamps, canals and tidal plains but they are not known to transmit diseases to humans.

• Biting midges are active where there is minimal air movement, at dawn and dusk and they shelter amongst vegetation.
• Usually biting midges disperse only short distances from breeding sites. However, some species can travel up to three kilometres from breeding sites.
• Biting midges can enter human environments and rest on fences, fly screens, vegetation and wait for a blood feed. Only female biting midges attack humans. However both males and females feed on nectar.
• An egg batch can contain 30 to 100 eggs and are laid on mud, moist soil, decaying vegetation and in other organic environments. Larvae hatch in a few days and thrive in an organic habitat where they grow to pupate stage.
• An adult biting midge can grow up to 1.5mm to 4mm long. Biting midge life cycle takes 3 to 10 weeks, depending on the species and environmental conditions.

Biting midges can cause acute discomfort and irritation due to their feeding technique but are not known to transmit any diseases to humans.

Each bite can leave inflammation on the skin which fills with damaged skin tissue and anticoagulants (transferred in the biting midge’s saliva). These bites can trigger an allergic reaction in sensitive people.

General symptoms of the bite sites are swelling, redness, itching and severe irritation (severe irritation can lead to bacterial infection). Acute allergic reactions may require medical attention. Some local residents will build up immunity to biting midge bites over a period of time.

These insects play an important part in the ecosystem being a food source to native fish species. They can be a nuisance when housing developments are located close to biting midge breeding environments.

Useful tips

• Be mindful when planning outdoor activities during sunrise and sunset. Cover exposed skin or apply an insect repellent containing DEET or picaridin (these products must be used according to directions on the packaging).
• Keep vegetation around the house sparsely planted and to a minimum to improve strong wind flow.
• Increase air flow inside the house using ceiling fans or other air circulation strategies.
• Make sure all windows and doors are adequately screened. Carefully designed fly screens (ie smaller mesh) can assist residents in impacted areas.
• Use mosquito coils or insecticide vaporisers.

Environmental concerns

Biting midge life cycles start in environmentally sensitive ecosystems, using larvicide and pesticides can be harmful to the ecosystem, including native fish species. Biting midge larvae exist in substrates such as mud, moist soil, and other organic environments making it difficult to treat them. There are no approved larvicides for the control of biting midges.

Ballina Shire Council does not undertake a biting midge control program due to these reasons.

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Resources

• NSW Health - advice to protect against mosquitoes
• NSW Health - Mosquito Borne Diseases
• Ballina Shire Development Control Plan 2012 (see chapter 2)
• Conversation website -  why mosquitoes seem to bite some people more 
• The Arbovirus website - NSW Arbovirus Surveillance & Mosquito Monitoring Program