Insect screens for Cairns: midges, sandflies and mosquitoes

What a Cairns house is screening against: mosquitoes and midges

Two kinds of biting insect decide what mesh a Cairns house needs: mosquitoes, which carry disease, and biting midges, which mostly just bite.

Mosquitoes are the health reason. Queensland Health says towns in north and central Queensland with the dengue mosquito, Aedes aegypti, are prone to dengue outbreaks when travellers bring the virus in. That mosquito lives and breeds around houses and buildings, bites quietly during the day, and the advice is to screen living and sleeping areas. Ross River virus cases in northern and central Queensland turn up all year, with most between February and May.

Biting midges are the comfort reason. A Brisbane City Council medical entomologist's information sheet describes them as small biting flies about the size of a pin-head, often called sandflies, and says most pest species in Australia breed in the intertidal zone of estuarine creeks. Logan City Council passes on Queensland Health's advice that midges don't transmit disease to humans in Australia. The bites still itch, and Fraser Coast Regional Council says the discomfort comes from allergens in their saliva.

Hole size decides what gets through: midges pass standard fly screens

A screen stops any insect bigger than its holes, and a standard fly screen's holes are small enough for mosquitoes and too big for most midges. That's the whole reason midge mesh exists.

The Brisbane entomologist's sheet, published by Redland City Council, says plainly that biting midges are small enough to get through normal flyscreens. Logan City Council says the same thing in shorter words: midges can get through insect screens. Fraser Coast Regional Council's advice is to fit fine-mesh screens to windows and doors and to look for mesh with a smaller gauge than standard fly screens.

Mesh is sold by strands per inch, so a bigger number means more strands and smaller holes. Alspec, which distributes Phifer screening in Australia, lists its standard fibreglass at 18 by 14 strands and its Sandfly mesh at 20 by 20 strands, with a thicker yarn. Take the yarn out of each strand spacing and the standard mesh leaves holes of roughly 1.1 by 1.5 mm, while the Sandfly mesh leaves holes of roughly 0.9 mm square. Those are our own sums from Alspec's figures, rounded.

Security mesh and midges: compare the maker's hole size

Security mesh keeps mosquitoes out, but whether it stops midges comes down to the hole size each maker publishes. Strength doesn't come into it.

Amplimesh, a security screen maker, describes midge mesh as a tighter weave that gives special protection from midges, and says its own SupaScreen security mesh does the same. It gives the SupaScreen holes as 1.6 by 1.6 mm. By the sums above, that's larger than the holes in a standard 18 by 14 fibreglass, the kind councils say midges get through. Both statements come from published figures, so it's worth putting the question straight to whoever quotes a security screen: what is the hole size, and is this mesh sold for midges?

We don't have a published hole size for the SCREENGUARD 316 stainless or the PERFGUARD 2 mm perforated aluminium we fit, so this guide doesn't claim either one stops midges. Both keep mosquitoes and flies out. A Diamond Grille or Colonial Casting screen relies on the fibreglass fitted behind the grille or cast panel for insects, so it screens like a fibreglass flyscreen. Our range of mesh page covers what each one is for beyond insects.

Finer mesh costs some airflow and view

A finer mesh stops smaller insects and lets less air and light through, so a midge screen trades airflow and view for smaller holes.

The Brisbane entomologist's sheet says it directly: fine-meshed screens designed to keep midges out will decrease air flow and possibly light compared to a normal flyscreen, but they work without any ongoing insecticide. Alspec's own openness figures show the size of that trade. Openness is the share of the mesh that's hole rather than yarn. Its standard 18 by 14 fibreglass is 63% open. Its Sandfly mesh is 45% open, though Alspec says it still offers good airflow. Its UltraVue mesh, made with a finer yarn, is 73% open. Alspec lists it for windows with a view and finer insect screening; it is not the mesh Alspec sells for small insects.

In Cairns, where a house is often opened up for the breeze, that trade matters. A sensible split is a finer mesh on the bedrooms and the openings closest to mangroves or a creek, and a more open mesh where the view and the breeze count most. Logan City Council notes midges are less active when it's windy, so a breezy elevated room may need less.

Gaps around frames, tracks and pet doors let insects past good mesh

Once the mesh is right, insects get in through gaps, and any gap wider than the mesh holes lets through everything the mesh was there to stop. Queensland Government advice is to make sure insect screens are in good condition with no visible damage.

Walk each opening with these checks, preferably at dusk with a light on inside:

• Tears, holes or dents in the mesh, especially at pet height and around handles.
• Mesh pulling away from the frame edge, leaving a slot along one side.
• A sliding screen that has jumped its track or no longer closes hard against the jamb.
• A screen door that doesn't shut on its own and gets left ajar.
• A pet door flap that hangs open or no longer sits flat in its frame.
• Gaps where the screen frame meets uneven brick, timber or tiles.

Fixing the gaps: repair the screen before replacing it

Most gaps are a repair job, not a reason to replace the whole screen. Where the fibreglass keeps tearing because a dog puts a paw through it, pet mesh is the practical swap: a thicker, stronger fibreglass that gives a little rather than tearing, and it fits wherever standard fibreglass goes.

Sliding screens and doors are the other usual culprits. We do onsite repairs to locks, wheels, tracks and pet doors, which covers several of the checks above. A screen that sits off its track or a pet door that no longer sits flat leaves a gap you can see daylight through, and every insect the mesh was meant to stop can use it.

If the opening needs a pet door in a security screen, read our guide to pet doors in security screen doors first, because cutting one in changes how that door stands on compliance. The flap is also one more seam that insects can find.

If midges still get in: fans, treated screens and timing

Logan City Council says biting midges are among the hardest pests to control and cannot be eradicated, so a few habits help alongside the right mesh.

Moving air is the cheapest one. Logan City Council says ceiling and electric fans can create an area midges don't like, because their activity drops in wind speeds over 6 to 8 km/h.

Timing is the next. The Brisbane entomologist's sheet says intertidal midges are most active at dawn and dusk, and that close to breeding sites they bite throughout the day. Fraser Coast Regional Council puts its own midge season at September to April. That's their region's figure, not a Cairns one, so treat it as a guide.

Treating existing screens is the third option councils describe. Logan says spraying a residual surface insecticide on flyscreens helps stop midges coming in, and the Brisbane sheet calls the evidence anecdotal and says the treatment needs redoing about every six weeks. Queensland Government advice on surface sprays is to read and follow all directions and precautions on the product label.

Choosing for your house: start from the insect, then the opening

Decide which insect you're screening against, then choose mesh opening by opening.

For mosquitoes and flies, the meshes we fit do the job when they're in good condition. That includes the fibreglass in our flyscreens, which won't rust, rot or corrode, and the stainless or perforated security meshes. Queensland Health's dengue advice is to screen living and sleeping areas, so those openings come first.

For midges, ask for the hole size or strand count in writing, and compare it with the figures in this guide. A 20 by 20 strand mesh like Alspec's Sandfly is the kind of finer gauge councils describe. Expect less airflow and view through it.

If you also want the opening secure, our guide to fly screens, barrier screens and security screens explains what a tested screen adds. Every door and screen we make is made to measure in Cairns. Tell us which insects bother you and which rooms when you ask us for a quote, and we can talk through the mesh for each opening.