In just a few years, the invasive Asian tiger mosquito has swept across swathes of Europe and is now buzzing range of the UK
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For twenty-five years I’ve lived in southwest France and during that time I have seen a number of new creatures move into the countryside around my home. Some, such as the black-winged kite; a beautiful icy white raptor more often associated with sub-Saharan Africa, or the striking two-tailed pasha butterfly, which is more commonly associated with the Mediterranean, are undeniably a pleasure to watch even if I know they shouldn’t really be here.
Other recent arrivals, though, are somewhat less welcome. I’m writing this, having just come back into the house after an afternoon in the garden fighting a losing battle against weeds and brambles. I have little nicks and tears on my hands and legs from these brambles, but that’s not the only souvenir of the afternoon imprinted onto my body. I also have dozens and dozens of itchy mosquito bites. But these aren’t the bites of native mosquitoes. These are the bites of the tiger mosquito, a recent arrival to France, as well as much of the rest of southern Europe from Southeast Asia.
Although the Asian tiger mosquito is a tropical species, it has adapted well to Europe’s cooler, temperate climate and, in a stunning example of high-speed adaptation, it has started to hibernate over the winter while studies have shown that its eggs have become much more tolerant of the cold. The eggs are also very resistant to dry periods and can remain dormant for years as they wait for the right conditions to hatch. These adaptations have allowed it to spread very fast across Europe. To illustrate this point, just five or six years ago, tiger mosquitoes were rarely seen in my part of France. Today, though, there can be so many of these stripy black and white mosquitoes, and their appetite for human blood so unquenchable that, at times, it can be almost impossible to sit in the garden for more than a few minutes.
But why should swarms of Asian mosquitoes in southern Europe be of concern to someone reading this in the UK? The answer to that is simple. The tiger mosquito has England in sight.
Originally from tropical Southeast Asia, the Asian tiger mosquito (Aedes albopictus) has taken advantage of international shipping and travel, as well as climate change, to spread quickly around the world. Its worldly wanderings began in the 1960s and it was first recorded in Europe in 1979 when it was reportedly brought into Albania on a shipment from China. It has since become established in 13 European countries.
As far as the UK is concerned, the presence of tiger mosquitos in France is the most worrying. It was first recorded in France in 2004, and by September 2023, it had spread to every single region of mainland France, including parts of Normandy, from where it’s only a short buzz over the Channel to England. Indeed, since 2016, British authorities have detected the presence of tiger mosquitos multiple times in the southeast of England. So far, though, they’re yet to get a firm foothold in the UK, but most experts are in agreement that this will happen – sooner rather than later – and that they will spread across at least the southern parts of the UK.
And if this happens, it isn’t just itchy bites and unusable gardens that will be the worry. The tiger mosquito, which is active during daylight hours, carries some very serious diseases including dengue fever, chikungunya and zika.
Although malaria is the disease most associated with mosquitoes, dengue is the most common mosquito-borne disease nowadays. The symptoms of dengue are similar to those of malaria. It starts out with flu-like symptoms, and in most cases, this is as bad as it gets, but it can become serious and, in some cases, fatal. In 2023, there were 6.5 million reported cases of dengue worldwide, which was the highest figure ever recorded. For the moment, most European cases are imported, meaning they were contracted by a person while they were travelling outside of Europe, and then they were transported back home while carrying the virus. In 2023, there were 5,000 imported cases. But, the number of locally acquired cases of dengue is also on the rise within the EU. In 2022, there were 71 cases of locally acquired dengue, but in 2023, the number of cases had increased to 130.
Tiger mosquitoes and the diseases they carry aren’t the only mosquito worries Europe has. The yellow fever mosquito, which, as the name suggests, is a carrier of yellow fever (it’s also a vector of dengue, chikungunya, and Zika) reached Cyprus in 2022. While in March 2024, a locally acquired case of West Nile virus infection was reported in Seville, Spain and in Puglia, Italy, the malaria-spreading mosquito Anopheles sacharovi was identified by scientists earlier this year.
Once the tiger mosquito becomes established, it’s very hard to eliminate. Across Europe and other parts of the world there are experiments underway to work out a solution to getting rid of this invasive species. Simply spraying insecticide is highly unlikely to work. Firstly, the mosquito will simply buzz back in from an unsprayed area, and secondly, tiger mosquitoes have already gained resistance to many insecticides. Plus of course, spraying huge areas with a toxic substance is hardly good for the environment or us! Another option is to sterilise male tiger mosquitoes, but this is a labour-intensive, expensive and slow option that might not work on a countrywide scale.
A more promising solution currently under investigation is to contaminate males with the Wolbachia bacteria. According to the World Mosquito Programme, a trial carried out on Aedes aegypti mosquitoes in Indonesia led to a 77 per cent reduction in the incidence of dengue and an 86 per cent reduction in hospitalisations for dengue.
For the moment though, all we can do is report any suspected tiger mosquito sightings, do what we can to stop them spreading and learn how to protect ourselves from their itchy – and potentially deadly – bites.
How to prevent tiger mosquitos from proliferating?
- Avoid leaving pools of stagnant water outside. Change the water in vases and flower pots regularly, empty or remove the saucers under flowerpots. Or fill them with sand to keep them damp.
- Don’t leave buckets, gardening equipment, games or any other item that could hold water outside in a location where rain could fall onto it.
- Cover rainwater collection tanks with a mosquito net or cloth.
- Clean gutters to allow proper drainage and prevent the build-up of stagnant water.
How to avoid being bitten by mosquitos?
- Wear long, loose, light-coloured clothing.
- Use mosquito repellents when outdoors and put mosquito coils under outdoor chairs and tables.
- Sleep under mosquito nets or use a fan at night (mosquitos won’t be able to fly against the air movement it creates).
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