The warm summer weather can attract a host of flying, biting insects that can make it difficult to enjoy the sun-soaked west London getaways.
Along with mosquitoes and midges, there is an altogether larger threat - the horsefly, and their bites aren't half painful.
These insects, also known as clegs, have razor sharp jaws which cut into the skin rather than piercing it, causing a very tender bite.
It can take much longer to recover from a horsefly bite than from a midge or mosquito bite as the wound can become infected.
Some people even suffer extreme allergic reactions to horsefly bites. So here's all of the key information you need to know.
What is a horsefly?
Horseflies are large and dark, like normal housflies, but at around 1cm to 2.5cm in size, they can be slightly larger than your average bluebottle.
They're usually found near cattle, horse stables, ponds, pools, woodlands and grassy areas - hence the name.
Only the females bite as they need blood to produce eggs, but their diet isn't restricted to horses. They'll quite happily bite any large, warm-blooded mammal - including people.
They have jagged, saw-like teeth which slice open skin, then they release an anti-coagulant to stop the blood from clotting while they enjoy their meal.
How do I know if I've been bitten?
The Manchester Evening News has published a helpful guide, complete with plenty of rather gruesome pictures of horsefly bites, should you fancy swotting up.
Firstly, the bites are painful and itchy, so you'll know fairly quickly if you've been bitten.
Horsefly bites develop into large, red, itchy, swollen bumps within minutes. For most people, they're completely harmless, but they're extremely uncomfortable.
Some people also report feeling hot, weak, nauseous or dizzy. An infected bite can also result in redness, oozing and extreme pain.
Visit your GP if you're suffering from an infection.
In exceptional cases some people can suffer an allergic reaction with symptoms including dizziness, wheezing, difficulty breathing, a blotchy skin rash and severe swelling that may be visible in your lips or tongue.
If you suffer any of these reactions, you should seek medical help immediately.
What should I do if one bites me?
The most important thing is to keep the bite clean, because if bacteria gets into the skin it can become infected.
In very rare cases it can cause cellulitis, an infection of the soft tissues. It's best to clean the wound with antiseptic soap and warm water.
Apply an ice pack to help sooth the area and stop the itching.
Doctors normally recommend using an over-the-counter steroid cream containing hydrocortisone. Ibruprofen gel can also help ease any pain and swelling.
And it goes without saying that you should avoid scratching the bite. It won't stop the itching and could damage the skin, increasing the risk of developing an infection.
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