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Repellents and physical barriers: how each protects against mosquito bites

Mosticare Editorial4 Jul 20267 min readEU
a bug on a leaf
Shot by Robert Thiemann

There are two proven ways to stop a mosquito reaching your skin: put a tested repellent on the skin, or put a physical barrier between you and the insect. Skin-applied repellents such as DEET are effective and remain the standard advice for travel to areas where mosquito-borne disease circulates. Untreated nets, window and door screens, and removing standing water work by exclusion, keeping the mosquito away from the person rather than coating the person. Here is how each approach works, where each one fits, and the honest trade-offs of both.

Stopping a mosquito bite comes down to two mechanisms. You can put a tested repellent on the skin so the mosquito does not land and feed, or you can put a physical barrier between the insect and the person so it never reaches the skin at all. Almost every method recommended for personal protection is a version of one of these two ideas.

They are not rivals. Used together they cover each other's gaps. This piece explains how each one works, where each one fits, and the honest trade-offs of both, without pretending either is a complete answer on its own.

Repellents on the skin

A skin-applied repellent does not kill the mosquito. It interferes with the chemical signals the insect uses to find a host, so treated skin becomes hard to locate and unattractive to land on. DEET is the best known active ingredient, and it is effective: decades of use and testing place it, alongside actives such as icaridin (picaridin), among the repellents that public-health authorities recommend. For travel to regions where malaria, dengue, chikungunya or Zika circulate, applying an effective repellent to exposed skin is standard advice from bodies such as the UK Health Security Agency and the US Centers for Disease Control and Prevention.

Repellents are also well characterised for safety. National risk-assessment bodies, including France's ANSES and Germany's BfR, publish guidance on which actives and concentrations are appropriate, including for children, and on how to apply them safely. Paediatric guidance from the American Academy of Pediatrics sets out age thresholds and sensible limits for use on children. The short version of all of it: repellents work, and they are safe when used as directed.

The trade-offs are practical. A repellent has to be on the skin, in enough coverage, at the moment the mosquito is biting. It wears off and needs reapplication, especially after sweating or swimming. Missed patches get bitten. It is a chemical in contact with skin, which is why guidance is careful about concentration and about use on young children. And it protects the person who applied it, for as long as it lasts, and no longer. None of this makes DEET or icaridin a poor choice. It makes them an active layer that depends on correct and repeated use.

Physical barriers

A physical barrier works by exclusion. Instead of treating the person, it puts a mesh or screen between the mosquito and the skin, so the insect cannot reach a host inside the protected space. An untreated bed net over a sleeping area, insect screens on windows and doors, and covering or emptying the standing water where mosquitoes breed are all versions of the same idea: keep the mosquito and the person apart.

Source reduction belongs in this category because it removes the problem upstream. Aedes albopictus, the tiger mosquito responsible for most recent local transmission in mainland Europe, breeds in very small volumes of standing water, in saucers, buckets, blocked gutters and discarded containers, close to where people live (ECDC). Emptying those weekly removes breeding sites near the home. It is unglamorous, and it is one of the most effective things a household can do.

The appeal of barriers is that they ask nothing of the skin. There is no active ingredient to absorb, nothing to reapply, and nothing to inhale. An untreated net does not wear off in the middle of the night. For sleeping infants and small children, for whom the choice of skin repellents is more constrained, an intact net over the cot is protection that does not depend on a chemical at all.

The trade-offs are equally real. A barrier only protects the space it encloses: a net protects the bed, a screen protects the room, and neither travels with you to a restaurant terrace or a morning walk. Protection depends on the barrier being intact and correctly fitted, so a net with a hole, a screen with a gap, or a door left open defeats it. Barriers need the right size and periodic inspection. And in the daytime, when Aedes albopictus is most active, a night-time net does nothing for someone who is outdoors.

A regulatory distinction worth knowing

The two approaches sit in different regulatory worlds, and knowing which is which helps when reading a label. A repellent is a biocidal product: it contains an active substance intended to act against a harmful organism, and within the European Union it is regulated under the Biocidal Products Regulation (Regulation (EU) 528/2012). An insecticide-treated net is likewise assessed for its active substance, and at the global level the World Health Organization prequalifies insecticidal vector-control products such as treated nets.

An untreated physical barrier has no active substance. A plain mosquito net, a window screen or a fitted mesh works by geometry alone, so it falls outside WHO prequalification and is not a biocidal product under the EU regulation. That is not a gap in quality. It simply reflects that these regimes exist to evaluate chemistry, and an untreated barrier has none to evaluate. It is worth remembering when a claim on a package cites an approval that in fact applies only to treated or chemical products.

Why this matters in Europe now

Personal protection has moved from a travel concern to a domestic one across much of Europe. The tiger mosquito is now established in 369 regions across 16 European countries, up from 114 a decade earlier, and its distribution continues to expand (ECDC). In 2025, metropolitan France recorded 809 locally-acquired chikungunya cases and 30 locally-acquired dengue cases, transmitted within the country rather than imported (Sante publique France). By 1 January 2025, 81 of France's 96 metropolitan departments were colonised by the mosquito, though colonisation of an area is not the same as disease transmission in it (Sante publique France).

The climate trend points the same way. The mosquito's active season is bounded by temperature and daylight, with the insect entering autumn dormancy as temperatures fall below about 9.5 degrees Celsius and daylight drops under 13.5 hours (EEA Climate-ADAPT). As those thresholds are crossed later in the year, seasons lengthen. In January 2026 the European Commission reported peer-reviewed modelling finding that more European cities, among them London, Paris, Vienna, Frankfurt and Zagreb, are becoming climatically suitable for the tiger mosquito.

Chemistry alone will not hold this line indefinitely. Knockdown-resistance mutations linked to pyrethroid resistance (F1534C and I1532T) are spreading in European Aedes albopictus populations, concentrated in the eastern Mediterranean (Pichler et al., 2025). That is a direct argument for layering: when one tool erodes, the others still work. And the stakes are not only medical. A recent analysis found that arboviral outbreaks carry measurable health, economic and social costs even in countries where the disease is not endemic (Apouey et al., 2026).

Putting it together

The honest position is that neither approach is complete on its own, and the sensible response is to match the tool to the setting rather than pick a side.

For travel to areas with active mosquito-borne disease, and for anyone spending time outdoors during the day, an effective skin repellent is the layer that travels with the person. For sleeping areas, for infants and small children, and for the home and its immediate surroundings, physical barriers and source reduction do the work without putting anything on the skin or in the air. Most people, most of the time, are best served by using both: a repellent when exposed, a barrier where they rest, and no standing water left to breed the next generation.

What the evidence does not support is the idea that one measure makes the others unnecessary. A repellent does not remove the value of a net, and a net does not remove the value of a repellent when you step outside. Treat them as layers, keep each one intact and correctly used, and the gaps close.

Sources

Sources & citations
  1. UK Health Security Agency: mosquito bite avoidance advice for travellers.
  2. CDC Yellow Book 2026: mosquitoes, ticks and other arthropods (personal protection and repellents).
  3. American Academy of Pediatrics (HealthyChildren): insect repellents and children.
  4. ANSES: guidance on mosquito repellents, including use in children.
  5. German Federal Institute for Risk Assessment (BfR): health questions on repellents.
  6. WHO prequalification of vector control products: assesses insecticidal products such as treated nets; untreated physical barriers fall outside its scope.
  7. Regulation (EU) 528/2012, the Biocidal Products Regulation.
  8. ECDC: invasive mosquito distribution maps.
  9. ECDC: Aedes albopictus factsheet (biology and breeding habits).
  10. ECDC, World Mosquito Day 2025: Aedes albopictus established in 369 regions across 16 European countries, up from 114 a decade earlier.
  11. Sante publique France: 809 locally-acquired chikungunya and 30 locally-acquired dengue cases, metropolitan France, 2025 season (published 6 May 2026).
  12. Sante publique France: 81 of 96 metropolitan departments colonised by Aedes albopictus as of 1 January 2025 (colonisation, not transmission).
  13. EEA Climate-ADAPT: climatic suitability and season length for the tiger mosquito (autumn dormancy below about 9.5 degrees Celsius and daylight under 13.5 hours).
  14. European Commission (DG Environment), 14 January 2026: more European cities, including London, Paris, Vienna, Frankfurt and Zagreb, becoming climatically suitable for the tiger mosquito (reporting Radici et al., Global Change Biology, 2025).
  15. Pichler V et al. Tracking pyrethroid resistance mutations I1532T and F1534C in Aedes albopictus across Europe. Parasites and Vectors, 2025;18:506.
  16. Apouey B, Raimond V, Rouviere E, et al. From bites to ripple effects: the health, economic and social effects of arboviral epidemics in mainland France. IJID Regions, 2026;20:100922.

Correction policy: if any fact above is shown to be wrong, we will amend it in place with a dated correction notice. Contact corrections@mosticare.org.

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