The best sandfly repellent plan in Australia is simple: cover skin at dawn and dusk, put repellent on every exposed patch (especially ankles, feet and the back of the neck), and add moving air and fine mesh where you sit. Australian health departments point to DEET or picaridin, and PMD, the lemon eucalyptus active, has published field data against biting midges.
That is the short version. The longer version is about getting your evenings back: the sunset swim, the boat ramp at first light, the mangrove paddle, the campsite after dark. Sandflies are what usually end those moments early, and with a little planning they do not have to. For the broader picture across mozzies, ticks and every region, start with our guide to the best insect repellent in Australia. This post goes deep on one tiny insect.
Sandflies, midges and no-see-ums: same bite, different names
Here is something almost nobody explains: the word "sandfly" means different insects depending on where you are standing.
In Australia, what most people call a sandfly is actually a biting midge. WA Health describes biting midges (family Ceratopogonidae) as 1.0 to 3.0 mm long and "commonly, but incorrectly, referred to as sand flies." There are over 200 species in Australia, and only some of them are a serious nuisance. Only the females bite.
Cross the Tasman and the word changes meaning. In New Zealand, "sandflies" are black flies (family Simuliidae, genus Austrosimulium), a different insect altogether, according to Landcare Research and Te Ara. In the US, the same tiny biting midges Australians call sandflies go by another name: no-see-ums.
| Where you are | What locals call it | What it actually is |
|---|---|---|
| Australia | Sandfly, midge, biting midge | Biting midge (Ceratopogonidae), 1 to 3 mm |
| New Zealand | Sandfly | Black fly (Simuliidae, Austrosimulium) |
| United States | No-see-um | Biting midge (Ceratopogonidae) |
So when you search "sandfly repellent" or "midge repellent" in Australia, you are looking for the same thing. One routine covers both.
When and where sandflies bite in Australia
Biting midges are creatures of habit, which is good news for anyone planning a day outside.
When. WA Health says midges are most active in calm conditions and most prevalent around dawn and dusk, though they may keep biting through the night and on overcast days. Queensland councils add that they prefer humid, overcast weather. Far North Training notes peak activity at around 27 to 32°C with humidity.
Where. They are found near sandy estuarine and foreshore areas and mangrove swamps, especially in tropical and subtropical Australia (WA Health). They also travel: from a few hundred meters to several kilometers from their breeding sites. That is why a backyard well back from the water can still get a dusk visit.
The moon. This one surprises people. WA Health links adult midge emergence to new and full moon phases, so the days around those moons can bring more of them.
Planning around sandflies: the best hours for the beach, boat ramp and campsite
You do not need to cancel the sunset swim. You just need to know when the odds stack up. Each condition below comes from the WA Health and Queensland council guidance above. The more of them line up at once, the more you will want repellent on before you head out.
| Condition | Higher sandfly odds | Lower sandfly odds |
|---|---|---|
| Time of day | Around dawn and dusk | Middle of the day |
| Wind | Calm, still air | A steady breeze |
| Cloud and humidity | Humid, overcast | Dry, clear |
| Location | Estuaries, foreshores, mangroves, tidal flats | Further from breeding sites |
| Moon | Around new and full moon | Between the two |
A few ways to use it:
- Beach days: swim in the breezy middle of the day, and have repellent on before the wind drops at sunset.
- Boat ramp and fishing: first light on still water near mangroves is peak sandfly time. Treat your ankles and neck before you leave the car.
- Camping: pick a site that catches the breeze, and plan dinner with long sleeves ready for the hour around dusk.
What actually repels sandflies
Let us be straight about the evidence, because this audience reads labels.
What Australian health departments say. WA Health recommends repellents containing DEET or picaridin, and states plainly that "Natural or organic repellents are generally not as effective as DEET or picaridin." Queensland councils add that when midge numbers are intense, 15 to 20% DEET is more effective. If you want the full head-to-head on actives, our PMD vs DEET comparison walks through it.
What the PMD field studies found. PMD (para-menthane-3,8-diol) is the active derived from lemon eucalyptus, and it is a CDC-recognized repellent ingredient. It also has published field data against biting midges specifically:
- In a field trial against the Scottish biting midge (Culicoides impunctatus), a eucalyptus-based PMD repellent and DEET both gave 98% protection 8 hours after application. A second trial found 99.5% protection for PMD and 97% for DEET at 8 to 10 hours (Trigg, Journal of the American Mosquito Control Association, 1996). That product was a different, higher-strength PMD formula, not ours.
- In California, a lemon eucalyptus repellent was tested against Leptoconops biting midges, and half the subjects using it got no bites over 6 hours of exposure (Journal of the American Mosquito Control Association, 2006).
Why "natural" results vary. Not every plant-based product performs the same, and midge species differ. In South African trap tests, a citronella plus lemon eucalyptus oil product did not repel local Culicoides midges (Journal of the South African Veterinary Association). The lesson: a specific, measured active like PMD is a different thing from a vague "natural" blend, and results can still vary by species and place.
Where plant-based PMD fits
This is the part of the routine my co-founder Cassidy Huang, our formulator, cares most about. We spent two years developing Bloc Off with a Taiwan-based chemist, and the brief was always a repellent people would actually want to reapply.
Bloc Off spray uses 8% plant-based PMD from lemon eucalyptus. It has 6+ hours of lab-tested protection against mosquitoes and ticks. To be clear, we have not tested it against sandflies or midges specifically, so treat the field studies above as evidence for PMD as an active, not as a claim about our bottle.
What the formula does suit is the sandfly routine. It is water-based and alcohol-free, with aloe vera and chamomile and no added fragrance, so it sits comfortably on the thin skin of ankles, wrists and the back of the neck, the exact spots sandflies go for. Shiso (perilla) is in there too, a traditional botanical long associated with natural insect-deterrent uses that rounds out the plant-based formula. The protection itself comes from the PMD.
On nights when sandflies are thick, health guidance favors DEET or picaridin, and that is worth knowing. For everyday dawn and dusk outings, a plant-based PMD spray applied thoroughly and reapplied per the label is a routine many people find easy to stick with.
How to apply repellent for sandflies
Sandflies are tiny and they stay low and close. Coverage matters more than quantity. Work from the ground up:
- Ankles and the tops of feet. The number one target, especially in sandals on sand or grass.
- Lower legs. Anywhere shorts or a sarong leave skin bare.
- Wrists and hands. Easy to miss after you have sprayed everything else.
- Back of the neck and the hairline. Spray into your palms and smooth it on.
- Ears and around the jaw. Again, palms first, never straight at the face.
Reapply as directed on the label, and again after swimming or toweling off. The 4 oz (118 ml) spray bottle fits in a day pack, and Bloc Off wipes are easy to keep in a pocket, a beach bag or the tackle box for the boat ramp.
Beyond repellent: clothing, fans and fine mesh
Repellent works best as one layer of several. These come straight from WA Health and Queensland council guidance:
- Clothing. Wear long, loose-fitting, light-colored clothes around dawn and dusk. A light long-sleeve shirt and loose pants make the sunset hour far more pleasant.
- Moving air. Midges do not like air currents. Queensland councils note that ceiling and pedestal fans deter them, so a fan on the veranda or a camp site that catches the breeze does real work.
- Fine mesh screens. Standard insect screens let midges straight through. WA Health recommends fine mesh on windows, doors and tents if you live or stay near the water.
- Yard habits. Keep lawns short and vegetation sparse, and avoid gardening in the early morning and late afternoon.
A calm note on bites, since it is a common question: WA Health explains that sandfly bites may not itch for several hours, and reactions range from mild to more noticeable swelling that can last for days. Far North Training observes that local residents often become less reactive over time. If a bite is bothering you, a pharmacist or GP can advise.
Traveling? Sandflies in NZ and no-see-ums in the US
If you are heading to New Zealand, remember that "sandfly" there means a black fly, not a midge, so the insect behind the bite is different.
If you are traveling to the US or the Caribbean, where these same biting midges are called no-see-ums, our guide to the best bug spray for no-see-ums covers that trip.
Back home, our store serves Australia and checks out in AUD, so you can stock up before the next long weekend on the coast.
FAQ
What is the best repellent for sandflies in Australia?
Australian health departments recommend repellents with DEET or picaridin, and Queensland councils say 15 to 20% DEET is more effective when midge numbers are intense. PMD, from lemon eucalyptus, has published field studies showing strong protection against biting midges. Whatever you choose, coverage of ankles, feet and neck matters most.
Are sandflies and midges the same thing?
In Australia, yes. WA Health notes that biting midges are "commonly, but incorrectly, referred to as sand flies." In New Zealand, "sandfly" means a black fly instead, and in the US the same midges are called no-see-ums.
Why do sandfly bites itch more the next day?
WA Health explains that sandfly bites may not itch for several hours, so the itch often shows up long after you have left the beach. That delay is why prevention at dawn and dusk is worth it. If a bite is bothering you, a pharmacist can advise. For what the bites look like and how long they last, see our guide to midge bites in Australia.
Do sandflies carry disease in Australia?
According to Queensland Health, as quoted in Queensland council guidance, midges do not transmit disease to humans in Australia. They are a nuisance, not a health scare, which is a good reason to simply plan around them and enjoy the evening.
Does natural sandfly repellent work?
It depends on the active. PMD from lemon eucalyptus has published field data against biting midges. At the same time, WA Health says natural or organic repellents are generally not as effective as DEET or picaridin, and studies show results vary by midge species. Look for a measured active, not a vague "natural" blend.
Written by Tanya Lee, Co-Founder of The Superbloc, with Cassidy Huang, Co-Founder and Formulator. Sources: Western Australia Department of Health (HealthyWA, "Biting midge (sand flies)"), Queensland council biting midge guidance citing Queensland Health, Far North Training, Trigg (J Am Mosq Control Assoc, 1996), Carroll and Loye (J Am Mosq Control Assoc, 2006), Journal of the South African Veterinary Association, Landcare Research and Te Ara.