Wasp attack: One man went to A&E

When Gavan Naden dragged the mower from his shed, he was imagining neat borders and the smell of cut grass. That was before he unwittingly disturbed a wasps' nest and its 1,000 angry residents

If anyone told me cutting the lawn could be life-threatening, I'd have laughed into their Pimm's. It's one of those laborious jobs that can bring a smile to your face. The aroma of freshly mown grass and the satisfaction of neatly cut borders – more life-enhancing than life on the edge.

So basking in the aftermath of Andy Murray's magnificent victory and enjoying the hazy early evening sun, I seized the moment and dragged the lawnmower from the shed. The grass was going to get a Wimbledon makeover.

Near the path, there's a small pond that I dug out with my son a couple of years ago and surrounded with ridiculous animals and strange figures perched on tree stumps. Here the grass grew a little more wild.

Deciding a Murray win was officially the start of a good summer, this was going to be the deluxe no-holds-barred trim, right up to the water's edge. I pulled up a small log used as a plinth for a gnome and immediately sensed something was wrong. A couple of wasps appeared by my hand and the base of the wood began swarming with an angry dark mass.

I dropped the log and stepped away. But it was already too late. I felt a sting on the back of my leg, lashed out and was bitten on the finger. More bites on my legs. Then my arms, then my neck. Any exposed flesh was like target practice. And the more I flailed, the angrier these wasps got. At that moment, the concept of staying calm and moving in a slow, non-threatening way was a physical and mental impossibility. I was shouting and running as I headed for the house, just hoping the wasps would give up stinging me. I wanted this to be over.

By the time I got to the kitchen, the wasps were still going at me, by which time I was yelling not just from the pain of the stings, but from sheer terror.

Leaping into the shower I recovered my composure and began gently inspecting the growing wheals appearing around my body. Painful, but manageable I thought, just relieved to be away from the swarm. I lay on the bed and was daubed with antiseptic cream. There were around 20 puncture marks.

Then the real nightmare began. My face, armpits and groin all started to swell and redden, yet these were places where I hadn't been stung. A rash was spreading down the length of my now puffy arms and my left eye was closing. And then my fingers changed colour. First blue, then black. I knew this wasn't right.

Within half an hour, I was in Watford A&E department being ushered through to "majors" surrounded and carefully monitored by nurses and doctors to ensure I wasn't going into anaphylactic shock. A drop in blood pressure and breathing difficulties can result in death if not treated promptly. Thank God for the NHS.

For the next four hours, I was given antihistamine drugs and my vital signs were checked repeatedly. I was told I needed to stay in hospital until any chance of further swelling had subsided.

By midnight, I was back home, still swollen, still very sore. But not in danger. However, my life has changed. I was warned by the doctor that I must now carry an EpiPen, a device used to deliver a measured dose of adrenalin, because if ever I am stung by a wasp again, even just one sting, there would be no knowing how my body would react. This shot of adrenalin, which I must self- inject, would buy valuable time in seeking medical help.

The following day, the council pest-control man arrived armed with a very long metal pole and a marvellously cavalier attitude. He sprayed the area with wasp-killer powder and discovered I had torn the wasps' nest in two, destroying their home. No wonder they were angry. And when I asked how many wasps the nest contained, he casually replied: "Around 1,000."

London Zoo's head of invertebrates, Dave Clarke, is a great fan of wasps and not at all surprised by the reaction of the wasps in my garden. "They are fascinating creatures, but not that clever. If they're annoyed, they want to get you back for destroying their nest. They are on the offence – it's their form of defence."

His advice for anyone in my situation is to get well away as quickly as you can. "If you disturb the nest, they are going to be really p****d off. And slowly walking will probably not work. If it was me, I'd leg it as quickly as possible and get inside and shut the door."

Only female wasps sting. The males have a fairly easy life, eating and sleeping. The intricate nests are often found in tree cavities, lofts, or holes in the ground and, if undisturbed, the inhabitants are unlikely to be noticed until the autumn.

"That's when the nest dies back," Clarke said. "Then they tend to go on a feeding spree. They go for sugary things, such as drinks and ice cream, and it's not that they want to attack us, they just want the sugar."

If stung, most people will feel sore in the area of the bite. However, Moira Austin, from the Anaphylaxis Campaign, said it was protein in the venom that causes the allergy. "We still don't understand why some people become allergic to stings, while others don't," Austin said.

"There is no definitive answer. If you're allergic, the body reacts inappropriately. Some people faint, have facial swelling, urticaria and their blood pressure drops – this is a medical emergency. It's important to call 999 and not move around. Standing up when you are in this condition can prove fatal."

Really severe cases are prescribed steroids, fluids and oxygen. My prompt arrival at A&E had saved a great deal of trauma – and maybe even my life.

For an uneventful summer, I've been told in future to keep my feet, arms and legs covered and stay away from rubbish. Try not to swat and try not to panic. And I'll add one of my own. Get someone else to cut the lawn.