Health officials have begun enhanced surveillance after invasive mosquitoes and larvae were detected at homes in east London, but UKHSA says the risk to the public remains very low.
Information checked on 4 September 2026. The investigation and surveillance work are continuing, so official advice may be updated.
At a glance
| Species | Aedes aegypti, sometimes called the yellow fever mosquito |
| Where found | Residential properties in east London |
| Why it is significant | This is the first confirmed breeding of the species in the UK |
| Public-health risk | Assessed by UKHSA as very low |
| Human infections | No infections have been linked to the mosquitoes |
| Nearby public spaces | No mosquitoes or larvae have been detected in nearby public areas |
| Established in the UK? | No. UKHSA says the species is not established and the normal UK climate remains too cold for long-term survival |
| Oxfordshire | No detection in Oxfordshire has been announced |
| What residents can do | Remove small collections of standing water and report unusual mosquitoes through Mosquito Watch |
| Report a mosquito | Use the UKHSA Mosquito Watch service |
The UK Health Security Agency has launched additional trapping and monitoring after invasive Aedes aegypti mosquitoes were found breeding in the UK for the first time.
Adult mosquitoes and larvae were detected at residential properties in east London following a report made through UKHSA’s Mosquito Watch citizen-science scheme.
Control measures have been introduced to destroy the larvae and reduce the possibility of further breeding. The surrounding area will continue to be monitored for additional mosquitoes, eggs or larvae.
UKHSA has not disclosed the exact properties or neighbourhood involved. It says there is currently no evidence of the species in nearby public spaces.
Why the risk is considered very low
Aedes aegypti can transmit viruses including dengue, chikungunya, yellow fever and Zika in parts of the world where those infections are already circulating.
However, finding the mosquito does not mean that any of those diseases are circulating in London.
UKHSA says there is no evidence that the mosquitoes have caused a human infection and has assessed the risk arising from the discovery as very low.
The species does not transmit malaria.
Dr Jolyon Medlock, Head of Medical Entomology and Zoonoses Ecology at UKHSA, said the insects were believed to have arrived accidentally.
Mosquitoes can be transported between countries in vehicles, luggage, imported plants and other goods. A warm local environment and small containers of water may then give an imported mosquito an opportunity to lay eggs.
UKHSA says recent heatwaves may have helped the insects survive and breed temporarily, but the overall British climate remains too cold for the species to persist over the long term.
Breeding does not mean the mosquito is established
The discovery of larvae shows that local breeding has taken place, making this finding more significant than the detection of a single adult mosquito or a small number of imported eggs.
It does not, however, demonstrate that a permanent, self-sustaining population has become established.
For a mosquito to become established, it would need to reproduce successfully over a longer period and survive seasonal conditions, including winter.
Aedes aegypti is adapted to tropical and subtropical climates and does not have the same ability as some other invasive mosquito species to place its eggs into a winter resting state.
UKHSA says it has not survived a winter anywhere in northern Europe and is not expected to become permanently established in England under the current climate.
Officials nevertheless expect incursions to become more frequent as temperatures rise and periods of warm weather become longer.
What is Aedes aegypti?
Aedes aegypti is a small, dark mosquito originating from Africa and now found across many tropical and subtropical regions.
It is sometimes known as the yellow fever mosquito because of its role in transmitting that disease in parts of the world where the virus is present.
The mosquito has white bands on its legs and pale markings on its back. The most distinctive marking can resemble the shape of a lyre against the darker body.
It is active during the daytime and around dawn and dusk and is closely associated with homes and other areas occupied by people.
Its larvae can develop in relatively small quantities of water, including water held in buckets, plant-pot saucers, blocked gutters, tyres and uncovered water containers.
Aedes aegypti is not the same species as Aedes albopictus, commonly known as the Asian tiger mosquito. Both are invasive mosquitoes capable of transmitting some of the same viruses, but they have different biological characteristics and markings.
Expert examination may be needed to distinguish an invasive species from one of the many mosquitoes already found naturally in Britain.
What UKHSA is doing in east London
Control measures have been used to target the larvae and remove potential breeding habitats around the affected properties.
Under UKHSA’s national contingency arrangements, specialists can inspect an area extending approximately 300 metres around a detection.
Teams look for water held in places such as buckets, tyres, plant containers, drains and discarded objects. These habitats may be emptied, removed or treated where larvae are found.
Additional adult mosquito traps and egg traps can then be installed to establish whether any further insects remain in the area.
Monitoring is expected to continue for several weeks. The aim is to identify and eliminate any remaining mosquitoes before they have an opportunity to spread or produce another generation.
UKHSA works with local-authority environmental health teams, port health authorities, landowners and residents when responding to an invasive mosquito detection.
How invasive mosquitoes are monitored
UKHSA’s Medical Entomology and Zoonoses Ecology team has coordinated invasive mosquito surveillance in England since 2010.
Monitoring concentrates on places where imported mosquitoes are more likely to arrive, including airports, seaports, motorway service stations, freight centres and distribution hubs.
Surveillance also takes place in urban areas where the climate may provide suitable temporary conditions.
One of the principal monitoring tools is an ovitrap, a water-filled container designed to attract female mosquitoes looking for somewhere to lay eggs.
Traps are normally checked every two weeks between June and October, when mosquito activity is highest. Samples are then sent to specialists for identification.
The east London finding demonstrates the additional value of reports from members of the public. The initial sighting was submitted through Mosquito Watch rather than being found in a routine surveillance trap.
What the discovery means for Oxfordshire
UKHSA’s announcement relates to a localised finding at residential properties in east London. It does not report any detection in Oxfordshire.
There has been no announcement of special public-health measures or mosquito controls in the county as a result of the London discovery.
Oxfordshire residents can nevertheless support national surveillance by reporting an unusual mosquito and reducing small collections of stagnant water around homes, gardens, allotments and workplaces.
This advice is precautionary and can also reduce the numbers of native mosquitoes that cause nuisance biting.
Britain already has more than 30 native mosquito species. Seeing a mosquito in an Oxfordshire garden does not mean that an invasive species has arrived.
The species most frequently submitted through Mosquito Watch is the native Culiseta annulata, a relatively large and conspicuous mosquito that is often mistaken for an invasive tiger mosquito.
How to reduce mosquito breeding around the home
Many mosquitoes lay their eggs in standing water. Small containers can be particularly useful breeding habitats because they may warm quickly and contain few natural predators.
Garden mosquito checklist
Clear gutters and drains: Remove leaves and debris so rainwater can flow away rather than forming stagnant pools.
Empty small containers: Tip water out of buckets, plant-pot saucers, toys, wheelbarrows, open bins and discarded containers.
Check tarpaulins and covers: Arrange them so rain drains away instead of gathering in folds.
Cover water butts: Use a close-fitting lid that prevents adult mosquitoes reaching the water.
Maintain paddling pools: Drain and refill the water every few days when the pool remains in use, and empty it when it is no longer needed.
Refresh bird baths: Replace the water every few days so larvae do not have time to develop.
Store tyres under cover: Tyres can hold small quantities of water for long periods and are recognised mosquito breeding sites.
Do not automatically empty a healthy pond: Permanent ponds can support insects and other predators that feed on mosquito larvae. Maintain the pond rather than treating it like a small stagnant container.
UKHSA’s complete advice is available through its garden mosquito-control guidance.
How to report a mosquito to UKHSA
Anyone who sees a mosquito in the UK can submit a report or photograph through Mosquito Watch.
The service helps officials understand the distribution of British species, investigate nuisance biting and detect invasive mosquitoes before they become established.
A clear photograph should be submitted with information about where and when the mosquito was found.
UKHSA has received more than 1,000 Mosquito Watch submissions since 2005.
Reporting a sighting
| Online report | Complete the Mosquito Watch form and upload a photograph |
| Useful information | Date, location, circumstances of the sighting and a clear photograph where possible |
| Physical specimens | Can also be sent after completing the online form and receiving a reference number |
| mosquito@ukhsa.gov.uk | |
| Medical advice | Mosquito Watch identifies insects but does not routinely test them for pathogens or provide individual medical advice |
UKHSA says a live specimen intended for posting should first be placed inside a container and left in a freezer for ten minutes.
It should then be sent promptly in a labelled, crush-proof plastic container with the reference number generated by the online form.
Mosquitoes collected from different places should be stored in separate labelled containers.
Previous Aedes aegypti detections in the UK
UKHSA describes the east London finding as the fourth modern-day detection of Aedes aegypti in the UK.
A single male was found in Merseyside in 2014, but follow-up investigations found no other specimens.
Eggs were detected at or near Heathrow Airport in 2023 and the species was detected there again in 2025. Enhanced monitoring found no evidence that it became established following either incursion.
There are also historical reports of the mosquito in Britain from 1865 and 1919. These older records are not included when UKHSA describes the east London incident as the fourth modern-day detection.
The new finding is different because both mosquitoes and larvae were identified at residential properties, providing the first evidence of breeding in the country.
What to do if you feel unwell
The east London discovery has not been linked to any human illness.
Anyone who becomes unwell after travelling to a country where dengue, chikungunya, yellow fever or Zika is circulating should seek appropriate NHS advice and mention their recent travel history.
UKHSA’s Mosquito Watch service cannot diagnose illness or test a submitted mosquito to establish whether it was carrying a virus.
People unsure which health service they need can use NHS 111 online or call 111. A life-threatening emergency should be reported through 999.
Frequently asked questions
Where were the invasive mosquitoes found?
UKHSA says mosquitoes and larvae were detected at residential properties in east London. It has not publicly identified the individual properties or a more precise location.
Have Aedes aegypti mosquitoes been found in Oxfordshire?
No Oxfordshire detection has been announced. The current finding relates to east London.
Is there a dengue, Zika or yellow fever outbreak?
No. UKHSA says there is no evidence that the mosquitoes have caused any human infection. The presence of a mosquito capable of carrying a virus does not mean that the virus itself is circulating.
How serious is the risk?
UKHSA has assessed the risk to the public from this finding as very low.
Is the mosquito now established in Britain?
No. Breeding has occurred within a local area, but UKHSA says the species has not become established and the typical UK climate remains too cold for long-term survival.
Could it survive the winter?
UKHSA says Aedes aegypti has historically struggled to survive temperate winters and has not overwintered in northern Europe.
Is Aedes aegypti the tiger mosquito?
No. The Asian tiger mosquito is a separate species called Aedes albopictus. Both have pale markings, so suspected sightings should be submitted for expert identification.
Does Aedes aegypti transmit malaria?
No. UKHSA says the species does not carry malaria.
Should I remove my garden pond?
Not necessarily. UKHSA says healthy permanent ponds can support predators that reduce mosquito larvae. The priority is removing or regularly refreshing water held in small containers such as buckets, plant saucers and bird baths.
How can I report a mosquito?
Submit a photograph and details through the UKHSA Mosquito Watch service. Physical specimens can also be sent after completing the online form.
Will UKHSA test a submitted mosquito for disease?
Not routinely. Mosquito Watch is primarily an identification and surveillance service and does not provide individual medical advice.
