UK mosquito numbers could increase in September due to warm weather

Experts are warning that mosquito numbers across the United Kingdom could rise this autumn. A stretch of warm, humid weather and heavy September rainfall has created ideal conditions for mosquitoes to keep breeding. Scientists say that both common native species and rare invasive ones may be affected. People are being urged to take simple steps to limit mosquito breeding around their homes.

Female mosquitoes need standing water to lay their eggs. When warm weather combines with heavy rain, puddles and pools collect in buckets, plant pots, and containers — giving mosquitoes plenty of places to breed. The London School of Hygiene and Tropical Medicine (LSHTM) said that recent temperature and humidity levels have been "perfect for a potential surge" in mosquito activity across Britain.

Dr. Yasser Qureshi, a researcher who studies mosquito behavior using artificial intelligence, explained why warm weather helps mosquitoes thrive. "Higher temperatures speed up egg, larval, and pupal development, meaning they can produce faster, while humidity helps them survive longer as the insects lose less water through evaporation," he said. Together, he warned, these conditions could have a real impact on mosquito populations in the UK.

This summer was already a busy season for insect activity across the country. NHS England reported a 35 percent jump in visits to its online advice pages about bites and stings between May and July. That spike shows how the warmer months are already affecting people's daily lives when it comes to insect encounters.

In the UK, the mosquitoes most likely to be active late in the year are native species. These include the common house mosquito, known scientifically as Culex pipiens, and the banded mosquito, called Culiseta annulata, which is known for being a persistent biter. These species are well-adapted to Britain's climate and can remain active even as temperatures begin to cool in autumn.

Health experts are also watching a more serious long-term trend. Climate change is slowly making Britain a friendlier place for invasive mosquito species — types that do not naturally live here. Earlier this month, officials confirmed that the invasive Aedes aegypti mosquito was found breeding inside homes in east London, marking the first time this has ever happened in the UK.

The Aedes aegypti mosquito is known to carry dangerous diseases, including Zika virus, dengue fever, chikungunya, and yellow fever. However, Dr. Jolyon Medlock of the UK Health Security Agency (UKHSA) said there is currently no evidence that these mosquitoes have caused any infections in people. He also noted that the mosquitoes have not been found in nearby public areas, which limits the risk to the general public.

The UKHSA says the Aedes aegypti mosquito cannot survive cold British winters — at least not yet. But scientists at LSHTM have called the discovery a "milestone event," meaning it is a significant moment that could signal future changes. They warn that as heatwaves become more common due to climate change, invasive mosquitoes may increasingly be able to survive and spread in the UK.

Dr. Qureshi pointed out that diseases spread by mosquitoes were once seen almost entirely in Africa, South Asia, and South America. As the UK grows warmer, he said, there is a growing chance these mosquitoes could survive here for longer periods of time. "That is a real risk," he added, urging the public and policymakers to take the issue seriously.

To help reduce mosquito numbers, the public is being asked to check their gardens and outdoor spaces. Emptying standing water from buckets, containers, and plant pots can take away the breeding spots that mosquitoes depend on. This simple step can help limit the growth of both native and invasive mosquito populations during warm, wet weather.