Mosquitoes on a High Floor: Why the 11th Storey Still Gets Bitten, and How They Get In

Someone on HardwareZone asked last year which HDB floor you need to stay above to stop getting bitten. They were on the 11th storey and getting bitten almost every night. The replies ranged from "13 and above" to "40" to "outer space", and the most repeated answer was the half-joke that mosquitoes take the lift.

There is no floor that solves it. But once you know how mosquitoes actually reach a high floor and get into your flat, you can shut most of the doors. Some of those are literally doors and windows, which is where we come in. Others are things no mesh can fix, and we will be straight about which is which.

Do mosquitoes really reach high floors?

Yes, though fewer of them. NEA runs a network of Gravitraps (small black traps that catch egg-laying female Aedes) along HDB corridors, on the 2nd, 5th or 6th, and 10th or 11th storeys of each block. A 2020 study of that trap data found low floors (1 to 4) had a higher abundance of mosquitoes than mid (5 to 8) and high (9 and above) floors, because Aedes prefer to lay eggs near the ground.

So Aedes are less common up high, not absent: the traps on the 10th and 11th storeys still catch them. If you are on the 11th, you are in the band with the fewest mosquitoes and still getting bitten, which tells you the problem is not how many are outside. It is how they are getting in, or whether they were ever outside at all.

The 8 ways mosquitoes get into a high-floor flat

Roughly in order of how often they turn out to be the cause on our site visits.

1. Breeding inside the flat

The uncomfortable one first. At dengue clusters in 2025, about 65% of the Aedes breeding NEA detected was inside homes. A mosquito that hatched in your bathroom never needed to reach the 11th floor.

Aedes needs very little: clean, stagnant water the size of a 20-cent coin is enough. NEA's Q2 2026 surveillance data lists the top five breeding spots found in homes as pails, flowerpots, flowerpot plates, vases and refuse bins outside landed houses. From our own visits we would add the floor trap in a bathroom nobody uses, the drip tray under an aircon unit or dehumidifier, and the saucer under the money plant on the service yard ledge. The B-L-O-C-K routine exists for exactly this.

2. Open windows, especially in the evening

The obvious route, and still the biggest one from outside. Aedes is most active around dawn and dusk, which is exactly when Singapore flats have windows wide open and lights on. Culex, the golden-brown night biter, breeds in blocked drains and comes in after dark. Height helps a bit here, but a lit window on the 11th floor is still a beacon.

3. The main door and the corridor

Common corridors are sheltered, shaded and lined with plants and scupper drains (NEA's Q2 2026 data lists corridor scupper drains among the top public breeding habitats). Mosquitoes rest there in the day and slip in when the main door opens, or stays ajar behind the gate for airflow.

4. The balcony or service yard door

Same idea, larger opening, often left open for hours through dinner. Kitchen and service yard windows are also the ones most often left open overnight, so they matter more than the living room window most people mesh first.

5. Riding up on people, bags and laundry

Mosquitoes rest on clothing and shoes, follow you into the lift and get off when you do. Laundry brought in at dusk is another taxi. This is the grain of truth in "mosquitoes take the lift". No screen stops it; a screen only stops the crowd outside from joining the one or two hitchhikers.

6. Gaps around grilles, frames and aircon piping

A window with grilles often has a channel of a few millimetres where the mesh or window frame meets the grille or wall, and the hole where aircon trunking passes through is another gap once the sealant crumbles. To a mosquito drifting along a wall, 5 mm is a doorway. Our environment guide covers how we deal with grilles.

7. Neighbours' plants and the block itself

If the flat next door keeps a corridor garden with saucers under every pot, mosquitoes are being produced a few metres from your window, which is why the HardwareZone thread kept circling back to "your neighbours". You cannot fix their flowerpots. You can report persistent breeding to NEA and screen your own openings.

8. Ventilation and rubbish chute openings

Uncovered toilet vents, kitchen exhaust openings and the rubbish chute hopper are less common routes, mostly in older blocks. A tight-fitting hopper and a covered vent close them.

Which of these does mesh fix?

Honest scorecard.

So mesh covers roughly half the list, and it is the half that involves the most mosquitoes over a year. It also keeps working: one user in a HardwareZone thread on mosquito mesh said they "haven't seen a single mosquito since" installing three years earlier, though others fairly called it a "dust magnet" that needs a wipe or wash every few months.

If you have already screened every window and are still getting bitten, do not buy more mesh. Go back to entry point 1 and check the floor traps, saucers and drip trays, then the corridor. And rule out the other biters: another HardwareZone thread had someone in Bukit Batok with 35 bites in three days, windows shut and NEA finding no breeding, and several replies suspected bed bugs. Bites in lines or clusters that you never see or hear happening point that way; our piece on when dengue mosquitoes bite has a quick mosquito versus bed bug comparison, and can mosquitoes go through window mesh covers troubleshooting from the mesh side.

What we would do on the 11th floor

If it were our flat, in this order:

1. Do the B-L-O-C-K walk-through once a week, and flush every unused floor trap so the water in it does not sit still.
2. Screen the openings that stay open longest: kitchen and service yard windows first, then bedrooms, then the balcony door.
3. Seal the grille gaps and the aircon piping hole at the same time.
4. Keep the main door shut once the corridor lights come on, or screen it.
5. Talk to the neighbours about corridor pots, or report persistent breeding to NEA.

For the screens, any of our retractable models handles the insect job, since every mesh we fit uses the same tight weave. The Base with polyester or fibreglass is the value pick for pure insect protection; step up to the Core or Pro if you have a cat, since insect-grade mesh will not survive claws. For the balcony, the Door model retracts sideways with a child lock. Our insect mesh guide covers weave sizes and prices, and our mesh doors guide covers door options.

If you want a second pair of eyes, WhatsApp us a few photos of your windows and we can give you a rough idea of cost. The site visit is free, no obligation, and we will point out any grille gap a mosquito would use whether or not you go ahead.

Frequently asked questions

Which HDB floor has no mosquitoes?

None. NEA trap data shows Aedes are most abundant on floors 1 to 4 and fewer from the 9th storey up, but traps on the 10th and 11th storeys still catch them. Mosquitoes reach high floors on people in lifts and by breeding in the flat or corridor itself. Height lowers the numbers; it does not remove the problem.

How do mosquitoes get in when my windows are closed?

Usually one of three ways: they are breeding inside (floor traps, aircon drip trays, plant saucers, pails, vases), they came in on someone's clothes or with the laundry, or they slipped in through the main door from the corridor. If bites appear in lines or clusters and you never see a mosquito, consider bed bugs before assuming mosquitoes.

Does window mesh work on a high floor?

Yes, for the same reason it works on a low floor: it closes the openings mosquitoes fly through. Fewer mosquitoes reach an 11th storey window, but the ones that do get in just as easily. Mesh does not help with indoor breeding, hitchhikers or the lift lobby, so pair it with the weekly stagnant-water check.

Are high floors safer from dengue?

Somewhat, because Aedes density is lower higher up, but only partly. Aedes breeding is often inside homes (about 65% at 2025 clusters), and a mosquito bred on the 11th floor bites on the 11th floor. Prevention is the same on every level: remove standing water, screen openings, use repellent during a cluster.

Sources

MeshMates product specifications are from our own product pages.

1. HardwareZone Forums — HDB must stay above which floor then won't kena mosquitoes? (Jun 2025). forums.hardwarezone.com.sg
2. Ong J. et al., PLoS Neglected Tropical Diseases — Gravitrap deployment for adult Aedes aegypti surveillance and its impact on dengue cases (2020). pmc.ncbi.nlm.nih.gov
3. NEA — Singapore Enters Peak Dengue Season, Public Urged to Stay Vigilant (16 May 2026). nea.gov.sg
4. gov.sg — Stop Dengue Now with B-L-O-C-K. gov.sg
5. NEA — Dengue Surveillance Data, Apr to Jun 2026 (PDF). nea.gov.sg
6. Clean and Green Singapore — Tips and FAQs (Block Dengue). cgs.gov.sg
7. NEA — Is it true that the Aedes mosquito does not bite at night? (NEA Vox). nea.gov.sg
8. NEA — Understanding Singapore's Mosquito Landscape: Why Different Species Matter (Annex B). nea.gov.sg
9. HardwareZone Forums — Mosquito Mesh (Sep 2025). forums.hardwarezone.com.sg
10. HardwareZone Forums — Mosquito problem, any tips? (Sep 2024). forums.hardwarezone.com.sg