Woken up covered in itchy red bite marks again? It’s probably mosquitoes you’re cursing – and those aren’t bite marks, but reactions to the grim little insects’ saliva where they sucked your blood.
Worldwide, there are 3,500 species of mosquitoes – including 36 in the UK and more than 200 in the US – and only the females are tiny, buzzing vampires.
Mosquitoes, it’s generally agreed, are a nuisance. Even in countries like the UK and US – where we don’t tend to worry about mosquito-borne diseases such as malaria, dengue or Zika – we’d all rather not be bitten by them.
But Prof James Logan warns that we will soon need to take the critters much more seriously. Logan is the head of the Department of Disease Control at the London School of Hygiene and Tropical Medicine (LSHTM), and CEO of pest and disease control science company, Arctech.
“As climate change carries on, we are seeing more mosquitoes that are capable of transmitting disease coming much closer to the UK and US, and that includes malaria mosquitoes as well as dengue mosquitoes,” he says.
“Although we don’t have those diseases circulating at the moment, we will in the future. It’s not a case of ‘if’, it’s a case of ‘when’.”
The US, says Logan, is “further ahead” than the UK; dengue, malaria and West Nile virus are already a growing problem.
And in May 2025, the UK Health Security Agency reported the first detection of West Nile virus in UK mosquitoes.
But, regardless of whether they’re disease-carrying or not, it seems like mosquito bites are becoming more common each summer – although there’s not a lot of scientific evidence for this.
What we do know is that the UK’s National Health Service (NHS) has reported larger numbers of people visiting their webpage on ‘insect bites and stings’ in the summers since 2021, and pest controllers and local authorities have reported increases in people being bitten in recent years.
“There’s a likelihood that there are more mosquitoes around because the weather is generally warmer, and that’s conducive to their breeding and activity,” says Logan.
Read more:
- Scientists discover what makes blood so tasty to mosquitoes
- Why do mosquito bites itch so much?
- Meet the microbe that is making mosquitoes malaria-free
Why mosquito bites are so itchy
So, we’ll likely see more of mosquitoes as the climate gets warmer – but why are their bites so bothersome?
It’s all because of the mosquito’s proboscis: an elongated, needle-like, sucking mouthpart.
“The mosquito’s attracted to your smell, heat and moisture, and when it lands on you, it inserts its proboscis into the skin,” explains Logan. “The end of the proboscis moves – it’s searching for a blood vessel, and when it finds one, it feeds from it.”
As it’s feeding, he explains, the pesky mosquito injects saliva into your bloodstream to stop your blood clotting and to numb the pain, so you don’t swat it away.
But all those spit chemicals cause an allergic reaction in your body, resulting in an itchy red lump.
“If you’re bitten by a certain species of mosquito for the first time, usually you don’t react very much,” says Logan. “But if you keep being bitten, you normally become sensitised – so you start reacting worse and worse – and then if you continue being bitten, your immune system adapts.”
When your immune system recognises a substance (such as mosquito saliva) as a threat, your white blood cells produce antibodies. So, the next time you encounter that substance, your immune system will automatically react – such as with redness and swelling.
This is called sensitisation, and it’s the same process that happens when you develop an allergy. But consistent exposure to that substance – called desensitisation – will lessen your reaction to it over time.
In seasonal countries, we’re only exposed to mosquitoes in the summer, so our bodies take longer to get used to them, “and that’s why our immune systems tend to overreact,” says Logan.
How to prevent mosquitoes getting to you
But now we know what we’re dealing with, how do we stop them biting us? The obvious solutions involve closing the windows or wearing long clothing – but, without the sweet relief of air conditioning, that’s hardly tempting at the height of summer.
Or, you could install insect-screens or mosquito nets in your bedroom, if you don’t mind the hassle.
“You can also try to get rid of any breeding sites,” says Logan, explaining that mosquitoes breed in stagnant water in volumes of anything bigger than a bottle-lid. You may want to go round your garden overturning flowerpots, buckets, and birdbaths, and getting rid of any rubbish or recycling that could be holding water.
Another option is wearing insect repellent. Logan mentions the chemical mixture known as DEET (an acronym for N,N-diethyl-m-toluamide) as “one of the best repellents on the market” and says it’s safe to use if you follow the packet’s instructions.
If you want a natural alternative, you can try oil of lemon eucalyptus, otherwise labelled as OLE or PMD, which Logan says works well. There’s also IR353 and picaridin.
Other essential oils are a bit more of a shot in the dark. A few studies have found that some varieties may work well, such a 2023 paper which concluded clove, cinnamon and geraniol oils were effective.
Still, Logan says, “People shouldn’t rely on those to protect themselves,” as they haven’t been proven to work.
If you want to go the extra mile, you could get ‘impregnated’ clothing. No, that’s not clothing that’s soon to give birth – it’s clothing that’s been sprayed or soaked with a repellent or insecticide (usually a substance called permethrin).
“There are also plugins that you put in your house that pump out an insecticide,” adds Logan. “But that’ll kill anything that comes in or lives there, like spiders or flies.”
What to do if you've been bitten
If a mosquito has already bitten you, there are some things to do – and avoid – to make the best out of an itchy situation.
“The first thing is to not scratch them,” says Logan, acknowledging that that’s a lot easier said than done. “All you’re doing there is making it dirty, and then you’re more prone to infection.”
In the worst-case scenario, mosquito bites can lead to severe infection, sepsis and even limb amputation, Logan warns.
If the bites are really irritating you, you can buy antihistamine or hydrocortisone cream from a pharmacy – but Logan says they’re not always effective.
“They work for some people and not others,” he says. “If it’s an antihistamine cream, you want to get that on very soon after the bite, because histamine is produced quite quickly after you’re bitten.
“But the problem is, a lot of people’s reactions to bites are delayed, and then it’s too late.”
In short, says Logan: “Keep it clean, don’t scratch it, take antihistamines, and hope for the best.”
Read more:
- Always bugged by mosquitos? Blame your body odour
- Five ways deadly diseases carried by mosquitoes have steered the course of human history
- Tinkering with nature: Billions of engineered mosquitos are getting released into the wild to fight disease
About our expert
Prof James Logan is the head of the Department of Disease Control at the London School of Hygiene & Tropical Medicine (LSHTM) and director of Arctech: a spin-out from LSHTM. Logan's work includes using sensors, insects and other animals as biosensors for identifying compounds that can be used as diagnostic markers for disease, developing nature-inspired tools for disease surveillance. His team was the first to identify the link between body odour and malaria infection.
