Dengue season checklist: 7 places mosquitoes breed at home

Dengue cases in Delhi NCR rise through September and October, and the mosquito responsible breeds in small amounts of still water, very often inside or right next to the home rather than in open drains or ponds. A short weekly check of a few specific spots does more to reduce risk than any single spray.

1. Cooler water

Desert coolers are one of the most common breeding spots in NCR homes. The tray holds still water that mosquito larvae can fully develop in within about a week.

• Empty, scrub and dry the cooler tray once a week during the season.
• If the cooler is not in regular use, drain it completely rather than leaving standing water in it.

2. Overhead tanks

A tank with a loose-fitting or cracked lid lets mosquitoes in to lay eggs even though the water looks clean.

• Check that the lid closes fully and has no gaps or cracks.
• Confirm the overflow pipe has a mesh cover, since this is a common entry point that gets overlooked.
• A clean tank on a regular schedule also helps; see how often to clean your water tank for the schedule and prices.

3. Flower-pot trays

The small plates under potted plants collect water every time the plant is watered, and that shallow pool is exactly the kind of still water Aedes mosquitoes prefer.

• Empty the plates under pots regularly, or fill them with sand so water drains through instead of sitting.
• Change water in vases and money-plant containers every 2 to 3 days rather than topping them up.

4. AC drip trays

Split and window AC units produce condensation that collects in a tray or drips through a pipe, and either can hold enough still water for larvae to develop.

• Check the outdoor unit's drip tray and the end of the drainage pipe.
• Any bucket or container placed under a drip pipe to catch water should be emptied regularly, not left to accumulate.

5. Blocked drains

Balcony and terrace drains that collect leaves and debris hold water after rain instead of draining it away.

• Clear leaves and debris from balcony and terrace drains regularly, especially after rain.
• Pour hot water down bathroom drains that are rarely used, since standing water in an unused trap can also breed mosquitoes.

6. Construction sites

Ongoing or paused construction nearby, including within a home undergoing renovation, often has open containers, pits or uneven ground that collects rainwater and sits undisturbed for weeks.

• If construction is happening on your property, ask the contractor to keep containers covered or drained.
• Report persistent standing water at nearby construction sites to the relevant municipal authority, since this is a common larger-scale source in a neighbourhood.

7. Old tyres and containers

Discarded tyres, buckets, broken pots and similar containers left outside collect rainwater and are notoriously good breeding sites because the water inside is shaded and undisturbed.

• Turn over or remove unused buckets, tyres and containers from the roof, balcony or yard.
• If something cannot be removed, drilling drainage holes or storing it under cover prevents water from collecting.

Your weekly checklist

• Cooler emptied and dried
• Tank lid closed and sealed
• Pot plates emptied or sand-filled
• Vase water changed
• AC trays and drip pipes clear
• Drains flowing, leaves cleared
• Nothing left holding water on the roof, balcony or yard

Indoor vs outdoor treatment

Checking breeding spots reduces new mosquitoes but does not remove adults already present, which is where professional treatment helps, and indoor and outdoor approaches are different.

• Indoor treatment typically combines a residual spray in resting spots around the home with a check of indoor breeding sources such as coolers, pots and AC trays.
• Outdoor treatment covers lawns, terraces, drains and society grounds, usually using fogging to reach mosquitoes resting in vegetation and open areas that an indoor spray cannot reach.

Thermal fogging vs cold fogging

The two fogging methods suit different settings. Thermal fogging produces a visible, smoke-like mist and is typically used outdoors across larger open areas such as lawns, terraces and society grounds. Cold fogging, also known as ULV, produces a fine mist without smoke, which makes it more suitable for indoor spaces and offices where a thick visible fog is impractical. Many homes use indoor residual treatment and cold fogging together with outdoor thermal fogging around the building, particularly in a housing society where common areas also need attention.

A combination of the weekly checklist above and seasonal treatment, indoors and outdoors, is the most practical way to reduce mosquito exposure through the dengue season rather than relying on either one alone.