The familiar scent of a Dhaka monsoon afternoon is no longer the same. The once-refreshing aroma of damp soil and tender foliage has all but vanished. So too has the life it once nurtured.
Among the many elements of this vanishing urban biodiversity is a unique species of mosquito known as Toxorhynchites, commonly referred to as the “elephant mosquito.” Unlike the infamous blood-sucking Aedes, this mosquito once played a crucial role in natural pest control.
These beneficial mosquitoes aided in pollination, and their larvae helped keep water bodies clean by feeding on bacteria. More importantly, they were natural predators of larvae from harmful, blood-feeding mosquitoes—thus controlling their population. Today, Toxorhynchites is nearly extinct from Dhaka’s water bodies.
In their absence, the city is dominated by aggressive, blood-feeding mosquitoes that pose deadly threats. Dengue has become a routine crisis, with the numbers too high to count on fingers.
“I remember seeing large larvae in the ponds near our village when I was a child. We used to call them ‘elephant mosquitoes.’ Now, I only see small, dark mosquitoes in Dhaka that leave you dizzy with a single bite,” said 34-year-old Maruf Islam, a resident of Hatirjheel who has lived in the capital for nearly 15 years. He was recently treated for dengue at Dhaka Medical College Hospital.
Mosquitoes are a constant nuisance around Hatirjheel, said Maruf, adding that even though the city corporation sprays insecticides, residents feel helpless under the persistent mosquito menace.
Losing nature’s “natural pesticide”
Professor Dr Kabirul Bashar from the Department of Zoology at Jahangirnagar University has been researching mosquito species and other insects for years. On Toxorhynchites, he explained that these mosquitoes are not hematophagous (blood-feeding). Instead, adults consume sugary substances like flower nectar, fruit juice, tree sap, and decomposing organic material. This diet helps them contribute to pollination and biodiversity preservation.
Visually, they are larger than common mosquitoes and have a distinctive metallic blue-green sheen that makes them easy to identify. In their larval stage, they become fierce predators—consuming the larvae of Aedes (the dengue vector) and Anopheles (the malaria vector). In this way, they naturally help regulate the population of harmful mosquitoes and prevent disease outbreaks.
“These larvae also contribute to natural waste decomposition,” Dr Bashar added. “But over the past decade, the species has become nearly extinct in urban water bodies.”
He blamed climate change, pollution, and unplanned urbanisation for the decline. “Protecting this species was the first line of defense in natural mosquito control. We’ve lost that.”
In Dhaka, mosquito means death
According to official figures, 1,163 people died of dengue in Dhaka alone in 2024. The number of infections reached nearly 170,000—up from about 138,000 in 2023, marking a 23% year-on-year increase.
Data from the Directorate General of Health Services (DGHS) dengue dashboard shows that more than 10,000 people were infected in the first six months of this year. In just the first two weeks of July, nearly 16,000 new cases were reported. The infection rate continues to climb across both Dhaka city corporations, with public hospitals admitting between 50 and 100 dengue patients every day.
Doctors at Dhaka Medical College Hospital say they are running out of ICU beds. With more patients arriving in critical condition—suffering from low platelet counts, dengue hemorrhagic syndrome, or shock syndrome—many are unable to secure hospital admission in time. Alarmingly, an increasing number of these patients are young, including school-going children.
A recent medical study titled “Clinical Profile of Dengue Patients, 2024” found that out of 107 dengue patients surveyed, 57% had standard dengue, yet 26% required platelet transfusions and 11% needed ICU admission. Nearly half of all infections occurred within Dhaka city.
The Directorate General of Health Services (DGHS) reported that on July 17 alone, 321 new dengue patients were admitted to hospitals across the country. The majority of these patients came from areas under the Dhaka North and South city corporations. Every day, new cases are reported from localities such as Khilgaon, Mugda, Mohammadpur, Mirpur, Uttara, and Dhanmondi.
According to the World Health Organization (WHO), climate change is fueling the crisis. Increased heat and humidity are expanding mosquito breeding grounds. Globally, the number of beneficial mosquitoes has declined, while dengue, Zika, and chikungunya viruses are on the rise.
In Dhaka today, a single oversight—like stagnant water left in a bowl—can bring tragedy to a household. A single mosquito bite may be enough to start a journey that ends in the hospital. To avoid that journey becoming a final farewell, what’s needed now is urgent public awareness, evidence-based action, and ecological restoration, said environmental scientist Professor Dr Ahmad Kamruzzaman.
One such tragedy struck the family of three-year-old Jisan in Dhaka’s Kuril area, where they have lived for years. In August 2024, Jisan developed a sudden fever, followed by internal bleeding. Doctors diagnosed him with dengue shock syndrome. Within just two days, the young boy passed away, plunging his family into grief.
“I had no idea how this deadly bite found its way to my child, even though we always kept the house clean,” said his father, Mamun Mia. “Jisan was the younger of our two children, born after 14 years of trying. He was a gift to us. But this unplanned and polluted city cut his life short. We are living in a city of death.”
Dhaka’s environment is ideal for Aedes mosquitoes
A 2018 study published in the International Journal of Parasites & Vectors—conducted by Jahangirnagar University in collaboration with the Malaria Elimination Initiative of UCSF—revealed that Aedes mosquitoes in Dhaka are now active both day and night. The species was found breeding in plastic cups, wooden crates of under-construction buildings, discarded tyres, bottle caps, and even stagnant water beneath air conditioners.
According to the study, 74% of mosquito larvae in residential neighborhoods were discovered in stagnant water collected in plastic and other artificial containers. The researchers concluded that conventional methods, such as removing containers or spraying insecticides, are no longer sufficient to curb the spread of these mosquitoes.
The World Health Organization (WHO), in its 2021 Climate and Vector Report, echoed similar findings—stating that Aedes mosquitoes are altering their behavior in response to climate change. No longer confined to daylight hours, these mosquitoes are now active at night as well.
Dhaka’s poor waste management system, open drains, and garbage-clogged water bodies have become ideal breeding grounds. Environmentalist Sharif Jamil, Member Secretary of the group “Dhoritry Rokkhay Amra (DHORA), said that even in areas with routine fogging or insecticide spraying, people are still falling sick with dengue.
“This is no longer just a health crisis—it is an environmental failure,” he said. “Plastic pollution, unplanned urban growth, and climate change have together created a deadly paradise for mosquitoes.”
Changing mosquitoes in changing climate
The WHO asserts that climate change and uncontrolled urbanisation are accelerating the spread of Aedes mosquitoes. Research also shows a disturbing trend: in regions where beneficial mosquito populations have declined, the spread of dengue and Zika has increased sharply.
Dhaka stands as a real and alarming example of this global pattern. Daily life here now teeters on uncertainty—where even a single mosquito bite could lead to death.
In response, researchers at the Insect Rearing and Experimental Station at Jahangirnagar University have begun work to create a sustainable breeding colony of beneficial mosquitoes. If successful, this project could pave the way for an eco-friendly and sustainable model of disease control. Public awareness is crucial, as many people may panic upon seeing these large, brightly colored mosquitoes without realizing they are harmless and beneficial. Rather than killing them, people should learn to protect these insects.
“People in Dhaka no longer fear just traffic or pollution—they now fear mosquitoes,” said environmental scientist Professor Dr Ahmad Kamruzzaman. “Yet once, nature provided the solution. Beneficial mosquitoes were our first line of defense. In losing them, we’ve made ourselves vulnerable. Now is the time to bring back nature’s lost soldiers—and make this city truly livable again.”
