Mosquito & Pest Control

Mosquito Control

The Shire of Broome maintains a comprehensive mosquito monitoring and control program across the townsite. The program is documented in the Shire of Broome Mosquito Management Strategy (first adopted by Council in 2011) which guides the Shire’s response to managing mosquitoes, customer service requests, the prevention of breeding and the spread of mosquito borne viruses.  The full document is available via the relevant link at the bottom of the page.

The Shire of Broome’s land area receives significant rainfall during the wet season and combined with heat and humidity, usually experiences an increase in mosquito numbers through January to April, until naturally occurring pooling water has evaporated. The Kimberley coast also experiences large tides especially during autumn and spring. Inundation of tidal flats and mangroves also contributes to an increase in mosquito breeding. The area is also affected by tropical lows and cyclones creating localised flooding events that will provide for an increase in mosquito breeding.

In and around Broome these features combine to provide an environment very suitable for mosquito breeding for over 12 different species of mosquito.  Some species are not harmful to humans, some bite us but don’t spread disease (nuisance species) and some have the potential to transmit harmful viruses to humans (pest species).  Because there is no vaccination to prevent mosquito borne viruses or a treatment cure once a person has the virus, protection from mosquito bites needs to be the first line of defence. 

In the Kimberley there are four main mosquito borne viruses of public health concern ie those that are a threat to human health. Ross River Virus (RRV) and the similar and usually less severe Barmah Forest Virus (BFV) which are carried in marsupials including kangaroos and wallabies, and probably other mammals, tend to be more common. These viruses can cause fatigue and tiredness and severe aches and pains and may last from many days to many months. Murray Valley Encephalitis (MVE) and Kunjin Virus (WNVKunjin) are carried in birds.  Of these MVE is the more serious virus and in severe cases can be fatal or leave a victim with permanent disability.  Only a small number of mosquito species in the Broome region can carry these viruses and transmit to humans.

What can I do to protect myself and stop mosquitoes breeding around my home?

·         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

·         Reduce outdoor activities during periods when mosquitoes are more active (dawn and dusk)

·         Ensure fly screens to doors and windows are fitted and maintained

·         Some spatial repellents might also be useful (pyrethroid containing coils etc)

Check your property for potential breeding sources

·         Empty pot plant bases weekly or fill the base with sand to absorb water

·         Plants that can hold water such as bromeliads 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; and

·         Birdbaths, ornamental pools and pet drinking bowls should be washed out weekly.

What does the Shire’s Health Service do to manage mosquito numbers?

Monitoring mosquito numbers, species and selected breeding sites

Throughout the year the Shire’s health staff trap mosquitoes at designated locations, and count and type them. This work is more frequent in the wet season or if there are complaints from the community,.  Checking for mosquito larvae (the water-based pre-adult mosquitoes) at recognised breeding sites is also performed.

Monitoring virus activity

The WA Department of Health maintains two sentinel chicken flocks in the Shire’s catchment.  The Shire and Nirrumbuk Aboriginal Corporation administer the Sentinel Chicken Program which uses the chicken flocks to monitor MVE and WNVKunjin activity in the environment.

People who are diagnosed with a mosquito borne virus have their details provided (confidentially) to a member of the Shire’s health team.  The environmental health officer will try to contact the person affected (by telephone or mail) to complete a questionnaire about the symptoms, likely places of exposure to mosquitoes and other relevant information which is provided to the Medical Entomology department within the WA Department of Health.  This helps inform state and local government authorities on disease trends and control measures.

Controlling mosquito numbers and risk minimisation

The Shire has a number of control options at its disposal.  These will only control numbers of mosquitoes and not eliminate them.  Eliminating harmful mosquitoes is not possible and eliminating mosquitoes entirely is not desirable as they have a role in plant pollination and as food for other animals. The controls include:

·         Cultural controls – Fight the Bite with its 3 key messages of cover up by wearing loose fitting, light coloured clothing, repel biting insects with insect repellents containing DEET or picaridin and clean up sources of standing water around the home.  This is the first line approach as mosquitoes are always present and more plentiful in the wet season.

·         Chemical controls – These can target mosquito larvae and adults.  For larvae the options include a growth inhibitor which dissolves in water and is suitable in clean water preventing larvae from maturing to adults; and a surface treatment which stops the larvae attaching their breathing tube to the water surface preventing them from breathing.  For adult treatments surface sprays and fogging are the main approaches.  These are less specific than the larvacides and can kill other insects that are exposed.  For this reason fogging is generally done at dusk (or dawn) when mosquitoes tend to be more active and other insects are less active.  Shire buildings are sprayed with surface spray periodically in the wet season.  When mosquitoes seek cool shade by landing under the eaves of the buildings they are targeted by the surface spray and die.

·         Biological controls – These are bacterial larvacides which target some mosquito species invading the larvae, destroying their digestive system and killing them.  These are quite specific in targeting mosquito larvae but are used carefully to avoid resistance to them developing.

·         Physical controls – These include modification of drainage systems or channelling in wetlands to improve drainage and alter water flow to interrupt the breeding cycle of mosquitoes.

It is important to note that mosquitoes are very versatile across the 12 or more species found here and different species can breed in fresh, brackish or polluted water.  In addition, some can travel large distances – up to 50km – although others do not move far from the neighbourhood in which they were bred.

The Shire carefully reviews the prevailing conditions in choosing which control measure and when to apply it.  Shire health officers also consult with the Medical Entomology team in the WA Department of Health to ensure that the choice of control has optimal impact on mosquitoes and minimal impact on the environment including other animals.

Fogging as a treatment option will only occur during a disease outbreak and/or following a major climatic event where the risk to public health of the community as a whole outweighs the risk to the environment from application of the adulticide.  The following is a list of key triggers that are considered before fogging (note that more than one trigger would be needed):

·         High number of complaints from the public to the Shire

·         New detections of Murray Valley Encephalitis and/or Kunjin Virus in sentinel chickens

·         Above average notifications of human cases of mosquito borne viruses

·         Above average rainfall

·         Trapping mosquito species that transmit disease in high numbers and as recommended for adult control by the Department of Health.

Mosquito life cycle and why mosquitoes need a blood meal?

The mosquito lifecycle includes a water phase as well as the adult mosquito phase.  It is only the adult female mosquito that bites because it requires a blood meal (protein) to produce eggs. Eggs are laid on or very close to standing water and the larvae (sometimes called wrigglers) go through 4 growth stages before becoming pupae (sometimes called tumblers). Adults emerge from the pupae on the water surface.  This is why managing standing water around your property is important.  Eliminating free standing water removes possible breeding sites.  Some adult mosquito species can travel significant distances in search of a blood meal but most species average 2-5km. Mosquitoes are attracted to carbon dioxide (exhaled breath), warmth, body odour, perspiration and light.

Mozzie-Lifecycle.jpg

If you have a mosquito problem at your home or place of business it is more than likely to be a localised problem caused by one or more of the factors listed above. As mosquitoes can be carriers of debilitating and even potentially fatal diseases, it is very important that the community take responsible action to eliminate breeding sites around the home and work place.  Local Government focuses on mosquito management on public land. Individuals have responsibility for management on their own property and for protecting themselves and their families from mosquito bites.

Mozzie and Midgies

Many new people to town or visitors confuse mosquito bites with midge bites. These biting midges are smaller than mosquitoes and do have a similar appearance.  While the midge bite can be irritating and its bites can become infected in susceptible individuals, midges are not known to spread disease.  To know more about biting midges please see the following link: Protecting yourself from biting midgies

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