What are biting midges?
Biting midges are tiny flies, about the size of a pin head.
They are well-known for the severe reaction that some people have to their bites.
Often they are incorrectly referred to as sandflies.
More than 200 species of biting midges are found across Australia, but only a few cause a serious nuisance to humans.
Biting midges may attack exposed skin in large numbers and their bites can be irritating and painful.
Only the females bite, using the blood they obtain as a protein source to develop their eggs.
Where do they breed?
Biting midges commonly breed around the edge of water bodies.
The adult female lays her eggs in places like:
- damp soil
- moist decaying leaf material
- muddy, sandy or vegetated substrates.
The biting midge lifecycle includes a worm-like (larval) and cocoon-like (pupal) stage before the adult emerges.
This can take 3 to 22 weeks depending on the environmental conditions and the species of biting midge.
The emergence of adult biting midges is associated with the new and full moon phases.
The adults can live for several days to months depending on the species.
When are they most active?
Biting midges are most active under calm conditions.
They tend to bite around dawn and dusk, but may continue to bite through the night. On overcast days they are also known to bite throughout the day.
Where are they found in WA?
Biting midges live in many coastal and inland areas of Western Australia.
They are most commonly found in tropical and sub-tropical parts of the State near sandy estuarine and foreshore areas and mangrove swamps.
They are very common in some coastal areas of north-west WA.
Many species will only travel a few hundred metres from their breeding sites, while others may travel several kilometres.
What are the health impacts?
Biting midges are not known to transmit any human diseases in Australia.
However, bites often cause a severe local (allergic) reaction and can be painful and/or irritating for some people.
The severity of the reaction varies from person to person.
People who are regularly exposed to biting midges may become desensitised over time, eventually experiencing only a very mild reaction or no reaction at all.
Others, including tourists, may experience a severe reaction with red, swollen bites measuring several centimetres in diameter.
Some people can be unaware they have been bitten as the itching may not commence for some hours.
The bites are usually painful and itchy.
They may also form blisters, become weepy and persist for days or weeks.
What treatments are available?
Applying an ice pack or using a mild antihistamine may provide some relief.
Secondary infections can result from scratching the bites and may require the application of antiseptic cream or antibiotics.
In severe cases, medical advice may be required.
Can biting midges be controlled?
Biting midges are one of the most difficult groups of insects to control as no chemicals are currently registered in Australia to control their breeding sites.
The large size of these sites also makes chemical control unrealistic.
Adult midges can be temporarily controlled using insecticides (fogging), but once the chemical droplets have settled, midges can re-infest treated areas.
Residual chemical sprays can be applied to places where biting midges may rest, such as the walls of your house, shade-cloth awnings, insect screens and vegetation to help reduce adult numbers.
Some residual spray products can control biting midges for up to 6 weeks, depending on environmental conditions.
It is important to remember that repeated use of residual sprays can have a negative impact on other insect and spider populations.
Always read the label and apply residual sprays in accordance with the manufacturer’s instructions.
How can I avoid being bitten?
Cover up and use repellents
- Avoid being outside around dawn and dusk and at other times if biting midges are active.
- Cover up with long, loose-fitting and preferably light-coloured clothing.
- Insect repellents are an important way of protecting yourself against biting midges. When outdoors use an effective insect repellent if biting midges are active.
- Insect repellents containing either diethyl toluamide (DEET) or picaridin are the most effective. As a general rule, the greater the percentage of DEET or picaridin, the longer the product will remain effective.
- Always follow instructions on the label.
- Choose a repellent with an appropriate concentration of DEET or picaridin to match the length of time you are outdoors.
- Apply directly to skin (except face) and spread evenly with hands.
- For face application, apply first to hands and then spread evenly on face, avoiding mouth and eyes.
- Repellents will not be as effective if applied sparingly to the skin.
- Repellents for children:
- Under 12 months – repellents containing DEET or picaridin are not recommended.
- From 12 months – repellents containing up to 10% DEET or picaridin can be used.
- Application guidelines for children:
- Do not allow children to apply repellent.
- Apply repellent firstly to the hands of the carer and then spread evenly to exposed skin of child.
- Avoid applying repellents to hands, near the eyes or mouth.
- Do not apply repellent under clothing.
- Lotion or gel repellents are the most effective. Always read the label. Apply and re-apply repellents in accordance with the manufacturer’s instructions.
- The best protection for babies and young children is protective clothing, fine mesh bed nets and other forms of insect screening.
- Ceiling fans or other air circulation devices may discourage midges from biting.
- Screen all doors and windows with a fine mesh. Biting midges are very small and can fit through standard fly screens.
Travelling and camping
- When planning holidays or outdoor activities choose locations well away from midge breeding sites.
- Be aware of the phases of the moon. Adult biting midges often emerge during new and full moon phases.
- Screen caravans, tents and other camping gear with a fine mesh.
- Increase the effectiveness of insect screens and other biting midge resting areas by using residual surface spray insecticides.
- Midges are well-known for the severe reaction that some people have to their bites.
- Biting midges may attack exposed skin in large numbers.
- They tend to bite around dawn and dusk.
This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.