Midges in Melbourne

Two very different insects called midges

Midges are small flies in the order Diptera, the group the Australian Museum describes as having a single pair of functional wings with the hind pair reduced to small balancing organs. Two families account for nearly everything Melburnians call a midge.

Biting midges belong to the family Ceratopogonidae, recorded in the Atlas of Living Australia and known regionally as sandflies or no-see-ums. They are tiny, between about one and three millimetres, and the females feed on blood. Their mouthparts are short and cutting, so the bite creates a small pool of blood at the skin surface, which is part of why the reaction is often out of proportion to the size of the insect.

Non-biting midges belong to the family Chironomidae, also catalogued in the Atlas of Living Australia. These are the insects behind the enormous swarms seen around lakes and wetlands. They look superficially like mosquitoes, with slender bodies and long legs, and the males often hold their front legs raised and carry feathery antennae. Adult chironomids have no functional biting mouthparts at all and take no blood; most do not feed during their brief adult life, which lasts only a few days. A useful field check is the resting posture: a chironomid at rest commonly holds its front legs up off the surface, and it has no piercing proboscis projecting forward from the head.

The lake swarms across Melbourne's west

Chironomid larvae live in the sediment at the bottom of lakes, wetlands, retention basins, drains and slow watercourses. Many are bright red, coloured by a haemoglobin-like pigment that lets them take up oxygen in low-oxygen mud, and they are widely known as bloodworms. They are a normal and ecologically valuable part of a healthy waterbody, feeding on organic material in the sediment and forming a large part of the diet of fish and waterbirds.

When conditions are right the population pupates and emerges more or less together. A run of warm days, a settled evening with light wind and an enriched, nutrient-heavy waterbody can produce an emergence of enormous numbers over a single night, and the adults gather into mating swarms that hang in columns over the water and over anything tall nearby. Suburbs built around constructed lakes and wetland reserves through Melbourne's west and north — the estate lakes around Point Cook, Werribee, Caroline Springs, Sanctuary Lakes, Craigieburn and the Altona foreshore among them — sit directly in the path of that emergence, and the swarms drift downwind onto whatever is nearest.

The behaviour that makes them a nuisance is their attraction to light and to pale surfaces. Adults settle in dense masses on white and light-coloured rendered walls, on flyscreens, on the underside of eaves and around any external light left on after dusk, and they come indoors in numbers whenever a lit door is opened. Dead midges accumulate on window sills, in pool skimmer boxes and along the base of walls, and the accumulated bodies and fragments add to the dust load in an enclosed space, which the Better Health Channel notes as a general consideration with insect-derived indoor allergens. They do not bite, they do not carry disease to humans, and they do not breed in or damage a house.

Biting midges and where they come from

Biting midges are the ones responsible for the bites. Only the females take blood, which they need to develop a batch of eggs, and they are most active in the hour or two around dawn and again around dusk, particularly on warm, still, humid evenings. Wind disperses them readily; a breeze above roughly ten kilometres an hour keeps them grounded, which is why a still evening after a hot day is the worst combination for anyone sitting outside.

The larvae develop in wet organic substrates rather than in open water: damp sand at the tide line, estuarine and mangrove mud, the saturated edges of salt marsh, the margins of drains and dams, and consistently damp soil rich in decaying organic material. That distribution explains the pattern of complaints around Melbourne, which concentrate along the bay from Altona and Williamstown through Mordialloc and Frankston and down the Mornington Peninsula, around the Werribee wetlands, and near estuarine sections of the Yarra and the Maribyrnong. Properties within a few hundred metres of that habitat get the pressure; the adults are weak fliers and generally stay close to where they emerged.

On a domestic property the same conditions can be reproduced in miniature. A perpetually damp garden bed, a poorly drained lawn area, a leaking irrigation line, an overflowing pot saucer, a neglected water feature or a compost heap kept sodden all provide the wet organic material biting midge larvae need. Finding and correcting those on-property sources is one of the few genuinely effective actions available.

Midge bites: the reaction and how to manage it

A biting midge bite usually starts as a small red spot and develops within a few hours into an intensely itchy raised lump. The reaction is frequently much larger than the insect that caused it, and in sensitised people the welts can reach several centimetres, blister, and continue itching for one to two weeks. Bites commonly appear in clusters on exposed skin — ankles, lower legs, wrists, the back of the neck — because a group of midges feeds in the same area. People vary enormously in how they respond, and a household can find one member covered in welts while another sitting beside them shows almost nothing.

For everyday management, healthdirect advises washing the area, applying a cold pack to reduce swelling and using a soothing preparation, with an oral antihistamine or a mild topical steroid appropriate for some people; a pharmacist can advise on which product suits. The most important practical step is avoiding scratching, because broken skin over a bite readily becomes infected, and a bite that turns increasingly red, warm, painful or starts weeping should be seen by a doctor.

Serious allergic reactions to insect bites are uncommon but real. The Better Health Channel sets out the range of reactions and when to seek help, and its guidance on anaphylaxis covers the emergency signs — difficulty breathing, swelling of the face or tongue, dizziness or collapse — which require an ambulance on triple zero. Biting midges in southern Australia are not considered significant vectors of human disease, which separates them from mosquitoes; anyone concerned about mosquito-borne illness will find the detail in our mosquitoes guide.

Why swarms form when they do

Both families emerge in pulses driven by temperature and by the condition of the water. Warm weather accelerates larval development, so a stretch of hot days brings a cohort through to pupation together, and the adults emerge over the following one to three nights. Still, humid evenings hold the swarm in place; wind breaks it up and pushes it downwind, which is why a household can be overwhelmed one evening and see almost nothing the next.

Water quality drives the size of the emergence. Nutrient-rich water, whether from stormwater runoff, garden fertiliser, waterfowl or organic material accumulating in a constructed lake, supports far larger larval populations in the sediment, so an urban retention lake with heavy runoff can produce chironomid numbers no natural wetland of the same size would. Warm shallow water with a soft organic bed is the most productive combination of all.

Lighting decides where they end up. Both groups orient strongly to light after dark, so a house with bright white external lighting between a lake and the prevailing evening wind will collect a far heavier settlement than an identical house two doors down with warm-toned lights on a timer. This is the single variable a household has the most control over, and changing it makes a noticeable difference within one evening.

What treatment can achieve, and what it cannot

We would rather be straight about this than sell an outcome that cannot be delivered. Neither we nor any other pest control company can eliminate midges from a suburb. The breeding habitat for both families is public land and public water — council wetlands, retention lakes, drainage reserves, the foreshore — and treating a waterbody is not lawful or practical for a private contractor. The larvae live in aquatic and semi-aquatic sediment that supports fish, frogs and birds, and broadly treating it would do real ecological harm for a short and partial result. Any company promising to rid a lakeside property of midges permanently is describing something that does not exist.

What can be done is reducing the pressure at your particular property, and that work is genuinely worthwhile. It has three parts. The first is source reduction on the property itself: finding and correcting the damp organic sites where biting midges are breeding within your own boundary, which for many households turns out to be a poorly drained garden bed, a leaking irrigation line, a neglected water feature or a chronically wet lawn corner. The second is a targeted barrier treatment applied to the vegetation, fence lines, eaves and shaded surfaces where adults rest during the day, which lowers the resident population around outdoor living areas for a period measured in weeks and needs repeating through the season. The third is exclusion and lighting: fine-mesh screening on doors and windows appropriate to insects this small, sealing gaps, and moving external lighting to warm-toned, shielded, timed or sensor-controlled fittings positioned away from doors.

Realistic expectations are part of the service. On a property backing directly onto a wetland during a mass chironomid emergence, treatment reduces settlement and makes the outdoor area usable without removing the swarm from the sky. On a property with an on-site biting midge source, correcting that source can change the situation substantially. We assess which of these applies before quoting, and we will tell you when we do not think a treatment represents good value for what you would be paying.

Reducing midges around your home

Start with the lighting, because it is free and it works quickly. Switch external lights to warm-toned globes, shield them so they throw light down rather than out, put them on sensors or timers, and move the main outdoor light away from the door people use. Keep internal lights off in rooms with open doors at dusk, and use the door on the sheltered side of the house when the swarm is up.

Screen properly. Standard flyscreen mesh stops chironomids and larger insects, and biting midges will pass straight through it because they are small enough to fit the apertures, so a finer mesh is needed where biting midges are the problem. Check that screen frames seal at the edges, repair gaps around window frames and weather seals, and fit brush seals to the base of external doors.

Remove the damp organic sites within your boundary: fix leaking taps and irrigation, improve drainage where water sits after rain, empty pot saucers, keep gutters clear, maintain or remove a neglected water feature and turn compost so it does not stay sodden. Where the property adjoins a wetland, avoid over-fertilising lawn and garden beds that drain toward it. For time outdoors during peak periods, cover exposed skin at dawn and dusk and use a repellent registered for personal use, following the label. Related outdoor insect advice runs through our pest library, and our fly control and mosquito control services cover the other insects that appear alongside midges through summer.

How Protech helps with midges

The visit starts with identifying which insect is involved, because the answer changes completely between the two families. The technician examines the specimens or the settlement pattern, confirms whether anyone is actually being bitten, and inspects the property for on-site breeding habitat: drainage, irrigation, water features, damp garden beds, compost and any standing water. We also look at the lighting layout, the screening and the position of outdoor living areas in relation to the nearest waterbody and the prevailing evening wind, since those factors determine how much difference a treatment will make.

Where a treatment is worthwhile we apply APVMA-registered products as a barrier to the vegetation, fence lines, eaves and shaded resting surfaces around the outdoor areas you use, following AEPMA best practice, and we set out a realistic re-treatment interval for the season along with the source reduction and screening work that carries the result between visits. Treatments we carry out are backed by Protech's pest-free guarantee within the terms we set out in writing, and we will be explicit about what the guarantee covers where a public wetland is the source, because we are not going to guarantee an outcome that depends on someone else's lake.

We have been working across Melbourne since 2001, including the lakeside estates through the west and the bayside suburbs where biting midges concentrate, and we are rated 4.8 stars from 384 Google reviews. If midges are making your outdoor area unusable or someone in the household is reacting badly to bites, call our team on 03 9449 4244 or request a free quote, and we will arrange an inspection and give you a candid assessment of what can be improved.

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