Mosquito Season: Repellent Strength, Coils and Netting

The coil is lit, the windows are shut against the evening damp, and the room fills with a smoke that smells like protection. Whether it actually is protection, and at what cost, depends on details most households never check.

We’ve already covered bite relief in our guide to mosquito bite home remedies with aloe and neem. This one is about prevention, before the bite happens, which matters more in dengue and malaria season than any after-the-fact remedy.

Repellent concentration actually matters

Not all repellents protect equally, and the label percentage is the difference between real protection and a false sense of it.

Citronella, neem oil and other plant-based sprays are genuinely pleasant and give some short protection, but they wear off fast, often within 30 to 60 minutes, which is why they work better as a top-up in a room already using a coil or net than as sole protection during an evening outdoors in dengue season.

Applying repellent correctly

1. Apply to exposed skin only, after sunscreen if you’re using both, not before.
2. Use about a 2 to 3 second spray per limb, rubbed in evenly, don’t soak the skin.
3. Avoid eyes, mouth, cuts and irritated skin.
4. Reapply after 4 to 6 hours for DEET, sooner if swimming or sweating heavily.
5. Wash off with soap and water once back indoors for the night, don’t leave it on overnight.

Babies and young children need a different approach

Under 2 months, skip sprays entirely, chemical repellents aren’t recommended at that age because infant skin absorbs more and the safety margin hasn’t been established. A well-fitted mosquito net over the cot, and long, loose cotton sleeves in the evening, do the job instead. From 2 months to 2 years, only use repellent when a doctor or pharmacist has confirmed it, at low concentration, applied by an adult’s hands and never on the child’s own hands, since toddlers put hands in their mouths constantly. Never apply repellent under clothing or on skin that will be covered, it doesn’t help and increases skin contact time.

Coil smoke indoors: the trade-off nobody mentions

A mosquito coil works by releasing a low dose of insecticide as it smoulders, and it does reduce bites in the room it’s burning in. The smoke itself is a mild respiratory irritant, similar in concept to any other slow-burning smoke, and burning it for hours in a small, sealed bedroom overnight is worse than burning it briefly in a ventilated room before bed and then airing the room out. Anyone with asthma, young children, or breathing sensitivity in the household is better off with a plug-in electric vaporiser or a net instead of a coil, since vaporisers don’t produce visible smoke particles the way coils do.

A simpler, lower-risk order of priority

Netting the cot or bed is the safest option with no chemical exposure at all, followed by an electric vaporiser in a ventilated room, then a coil used briefly with a window cracked, with repellent spray reserved for time spent outdoors at dusk, when mosquito activity peaks.

Netting the cot properly

A net only works if it’s actually sealed. Tuck all edges under the mattress or crib base so there’s no gap a mosquito can slip through, check for small tears monthly, and treat the net (or buy a pre-treated one) with permethrin if dengue or malaria cases are active in your area, following the product’s own instructions rather than a stronger concentration for “extra” protection.

Clothing and timing as a first line of defence

Aedes mosquitoes, the type that spread dengue, are most active in the early morning and late afternoon rather than only at night, which surprises a lot of people who associate mosquito risk purely with dusk and evening. Long sleeves and full-length trousers in light colours during these windows reduce exposed skin without needing any repellent at all, and are worth combining with repellent rather than treating as an either-or choice. Keeping outdoor play or errands to midday hours where possible, when Aedes activity is lower, is a small but genuinely useful adjustment during an active dengue season.

Standing water around the house matters as much as skin protection

No repellent routine fully compensates for a mosquito breeding site sitting a few metres from the front door. Aedes mosquitoes lay eggs in small amounts of clean, still water, a flowerpot saucer, an old tyre, a blocked drain, a bottle cap left in the yard, and can complete their life cycle in about a week during monsoon warmth. A weekly check around balconies, terraces and gardens for anything holding water, tipping it out or covering it, cuts the local mosquito population at its source rather than only defending against the ones already flying around.

Communal areas need the same attention

In apartment buildings and shared compounds, one neglected water tank lid or a communal garbage area with pooled water can undo everyone’s individual precautions. Raising this with building management or a residents’ group during dengue season is a genuinely effective, low-cost step that individual repellent use can’t replace.

Fabric treatment as an extra layer

Permethrin-treated clothing, either pre-treated or sprayed on by the wearer following product instructions, adds a layer of protection independent of skin repellent, particularly useful for school uniforms or outdoor work clothes during an active outbreak. It should never be applied directly to skin, only to fabric, and treated clothes should be laundered separately the first few washes as the label usually directs.

See our Season Shift hub for more seasonal prevention guides, and read about warning signs and honest platelet advice in our dengue myths article if mosquito season has already led to a fever in your household.