When a dengue [1] case appears in a Gulshan apartment block, the committee’s first instinct is to book a fogging round, and we understand why — it is visible, it is fast, and residents can see something being done. We will do it. But we will also tell you what it does and does not achieve, because a building that fogs monthly and never surveys its containers stays a dengue site indefinitely. Fogging kills the adult mosquitoes airborne at the moment the fog passes. It does not touch the eggs and larvae in the roof tank, the stairwell bucket, the AC drip tray on the third floor, or the flower pots on twelve balconies, and with a 7 to 10 day egg-to-adult cycle in Karachi summer, those refill the building within a fortnight. This page covers how we run dengue work across Block 1 to Block 13, alongside our Karachi-wide mosquito control service.
What fogging does, and what it does not
What it does. Ultra-low-volume fogging disperses a fine aerosol of Deltamethrin 1.25% that stays suspended long enough to contact flying adults. Where there is an active case in a building, that immediate reduction in the adult population genuinely lowers transmission risk in the days that matter — an infected mosquito that dies today does not bite anyone tomorrow. In an outbreak response, speed has value on its own.
What it does not do. The aerosol settles within a short time and leaves no meaningful residue on surfaces. It does not penetrate the water where larvae live. It does not reach mosquitoes resting inside flats, in cupboards or behind curtains, unless the flats themselves are treated. And it does nothing at all about the containers producing the next generation. This is why a building on monthly fogging still has mosquitoes — it is treating the symptom on a schedule.
What actually breaks the cycle. Source reduction and larviciding. Aedes aegypti [1] flies only about 100 to 200 metres in its lifetime, so the mosquitoes biting residents in Block 6 emerged in or immediately around Block 6. Find and remove the water, treat what cannot be removed, and the population collapses. Fog on top of that for immediate relief, not instead of it.
Where an apartment block actually breeds Aedes
The sites are different from a bungalow’s, and most of them are in shared areas no individual resident feels responsible for.
The roof tanks. The single largest reservoir on most Gulshan buildings. A lid that has gapped, a hardened gasket, or an overflow pipe with no mesh cap is an open invitation, and the water is warm, still and undisturbed between fills. We survey these first and pair the work with water tank cleaning in Gulshan-e-Iqbal where the tanks also need cleaning.
AC drip trays and drip points. Every split unit on the building drips through summer. Where it lands in a tray, a clogged drain channel or a ledge depression, it produces continuously replenished clean water — the ideal Aedes container. On a twenty-flat building that can be twenty separate sites.
Balcony pots, stairwell buckets and the water pump room. Plant saucers on balconies, stored water buckets in stairwells and utility areas, and standing water in the pump room floor. These are small volumes, which is exactly what Aedes prefers.
Blocked parapet and terrace drains. After rain a blocked roof drain holds water for days. It is out of sight, nobody owns it, and it is often the most productive site on the whole building.
Ground-floor and boundary water. Construction debris in the compound, an unused water feature, tyres, and the drain along the boundary. The drain is usually Culex rather than Aedes, but it drives the night-biting complaints residents raise in the same meeting.
How we run a building visit
Step 1. Source survey with the building manager. Roof, stairwells, pump room, compound and, where residents allow, balconies. We list every site found and photograph it, so the committee has a record rather than a verbal report. Where a site is inside a private flat we note it and ask the manager to circulate it, because a building cannot be cleared while a single balcony keeps producing.
Step 2. Source reduction on the spot. Trays emptied, drains cleared, buckets inverted, debris removed. Free, immediate, and more effective than anything else on the list.
Step 3. Larviciding what stays wet. Roof tanks get a Bacillus thuringiensis israelensis (Bti) tablet. Cry endotoxins bind to Aedes aegypti mid-gut receptors and kill larvae within 24 to 48 hours, WHO Class III and non-toxic at potable dosing, one tablet per 1,000 litres for roughly 30 days. Non-potable standing water, drains and the pump room get temephos or an IGR such as pyriproxyfen or methoprene, which stops larvae developing into biting adults.
Step 4 — ULV fogging, timed properly. Deltamethrin 1.25% ULV through the stairwells, corridors, basement, compound and roof. Timing matters: Aedes aegypti is a day-biter with activity peaks in the early morning and late afternoon, so fogging at those windows contacts far more of the target population than a convenient midday slot. We schedule building fogging for early morning or late afternoon for that reason, not for the residents’ convenience.
Step 5. Residual barrier on resting surfaces. Permethrin 10% EC on shaded stairwell walls, under-stair surfaces, the shaded side of the compound wall and the plant beds. Mosquitoes spend most of their lives resting, so a residual on the resting surface keeps working for weeks after the fog has dispersed.
Step 6 — Day 14 follow-up. Non-negotiable during an active outbreak. The egg-to-adult cycle is 7 to 10 days in Karachi summer, so a second visit at day 14 catches the generation that was already in the water at the first visit. Buildings that do one round and stop are the ones that call again in three weeks.
Notice, access and resident safety
Notice. Residents need 24 hours’ warning. During fogging they should stay inside with windows closed, keep children and pets in, cover or remove pet water and fish bowls, and cover any food left out. Aquariums need their air pumps switched off and the tank covered — pyrethroids are highly toxic to fish. We provide a notice text the manager can circulate on the building WhatsApp group.
Access. Roof, pump room, basement and stairwell access on the day, plus whoever holds the keys. Half the delays on building jobs are a locked roof and an absent chowkidar.
Re-entry. Common areas can be used again after about 30 to 45 minutes with ventilation. Anyone with asthma or a respiratory condition should stay clear for a couple of hours. We do not fog inside private flats unless the resident specifically asks and is present.
What a typical Gulshan building call looks like
An active case in a Block 10 building. The committee calls after a resident is diagnosed, and they want fogging that evening. We do fog, because reducing the adult population around a confirmed case has real value in the days that follow. But the survey almost always finds the reason: an unsealed roof tank, several AC drip trays, and a blocked terrace drain holding water since the last rain. The honest conversation is that the fog buys a week and the tank plus the drains is what stops it recurring. Buildings that take that advice generally do not call us back in the same season.
A pre-monsoon preventive round. The better version of the same job, booked in June before cases appear. Full source survey, tanks cleaned and Bti-dosed, drains cleared and larvicided, barrier applied, and a fogging round scheduled only if the adult population warrants it. It costs less than outbreak response and it works considerably better, which is the argument we make to committees every year.
Gulshan pricing
Priced on building size, number of floors and scope. Identical bands across Karachi — no locality premium and no outbreak surcharge.
ULV visit, single flat: PKR 3,500-6,500.
ULV visit, 2-3 bed flat or house: PKR 5,500-11,000.
Insect growth regulator added to the programme: PKR 150-400 per visit.
Whole-building programmes — survey, source reduction, larviciding, residual barrier and ULV across stairwells, roof, basement and compound — are quoted per building on flat count and roof-tank number, not off a per-flat rate.
The day-14 follow-up round is priced below the first visit, and during an active outbreak we treat it as part of the job rather than as an upsell. Full bands are on our fumigation cost guide.
Booking, and what happens on the day
WhatsApp +92-311-1101810 with the building name, your block, the number of floors and flats, and whether there is a confirmed dengue case. A confirmed case changes our scheduling priority. Price band and slot confirmed inside 30 minutes during business hours, Mon-Sat 09:00-21:00. Gulshan is 25-35 minutes from our Phase 4 office.
A two-person team arrives with a ULV machine, Deltamethrin 1.25%, Permethrin 10% EC for the barrier, Bti tablets, temephos and IGR for drains, survey kit and PPE. A fogging round on a mid-size building takes 45 to 90 minutes; the full programme with survey and larviciding is three to five hours. Circulate the resident notice 24 hours ahead. You will get a treatment record listing every product used and every site treated, which committees generally want for their file, and a photographed list of breeding sites found, including the ones inside flats that only residents can fix.
Questions Gulshan committees ask
We fog every month and still have mosquitoes. Why?
Because fogging only kills the adults airborne when the fog passes, and your building is still producing new ones. With a 7 to 10 day egg-to-adult cycle, a monthly fog leaves roughly three uninterrupted generations between visits. The tanks, AC trays, balcony pots and blocked terrace drains are the actual population source. Treat those and you will need far less fogging, not more.
A resident has confirmed dengue. What should we do first?
Book a fogging round for immediate adult reduction around the case, and a full source survey at the same visit, not as a separate job later. Aedes aegypti flies only 100 to 200 metres, so the mosquito that infected your resident almost certainly emerged on or beside your building, and the breeding site is still producing. The day-14 follow-up is essential in this situation rather than optional.
What time of day should fogging be done?
Early morning or late afternoon. Aedes aegypti is a day-biting mosquito with activity peaks at those two windows, so fogging then contacts far more of the population than a midday round. Fogging at a time that simply suits the schedule is one of the commonest reasons a round underperforms. Still air also helps the aerosol stay suspended, which is another argument against the middle of a windy afternoon.
Is it safe for children, elderly residents and pets?
With the standard precautions, yes. Residents stay indoors with windows closed during application and common areas are ventilated for 30 to 45 minutes afterwards. Anyone with asthma or a respiratory condition should stay clear for a couple of hours. Cover food, remove pet water bowls, and — this one matters — cover aquariums and switch off the air pump, because pyrethroids are highly toxic to fish. We do not fog inside private flats unless the resident asks and is present.
Do you treat individual flats or only common areas?
Both, but they are quoted separately. A building round covers stairwells, corridors, basement, compound and roof. Interior flat treatment is booked by the resident, and it is worth doing where someone is being bitten indoors during the day, because Aedes rests inside — in cupboards, behind curtains and under furniture, rather than outdoors.
Which Gulshan blocks do you cover?
Block 1 through Block 13, plus Gulshan Chowrangi, NIPA, Hasan Square and the University Road corridor, at identical published rates. Typically 25-35 minutes from our Phase 4 office. Where there is a confirmed case we prioritise scheduling and will usually get to you the same day.
Book dengue treatment across Gulshan-e-Iqbal Block 1-13
WhatsApp or call +92-311-1101810, or email contact@nestfumigationservices.com. We cover Gulshan-e-Iqbal Block 1-13, Gulshan Chowrangi, NIPA and Hasan Square from our office at Plot #14, 2/1 2nd Gizri Street, DHA Phase 4, Karachi 75500, Mon-Sat 09:00-21:00. ISO 9001:2015 certified; members of KCCI, SPMA and PPMA. See also our mosquito control service, the comparison of fogging vs larviciding, and pest control in Gulshan-e-Iqbal.
Saad Danish is a co-founder and director of Nest Fumigation Services Private Limited, a licensed pest-control and fumigation company based in DHA Phase 4, Karachi. He oversees the company's administration, client services, and marketing, working alongside NFS's technical team to deliver residential and commercial pest management across Karachi — from termite proofing and general pest control to HACCP and Sindh Food Authority compliance programmes for food, warehouse, and industrial clients. Nest Fumigation Services is ISO 9001:2015 certified and a member of the SPMA (Sindh Pest Management Association), PPMA, and the Karachi Chamber of Commerce and Industry.
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