SUN lovers have been warned to watch out for swarms of wasps, bees, hornets and other stinging insects.

The heatwave has meant a larger than average number of flying ants and other insects has hatched.

And already hospitals have had to deal with an increasing number of bites and stings.

One woman, who was stung by a wasp, said: 'I felt a sharp pain and within about 20 minutes my arm had begun to swell up and turn red.' Professor Lars Chittka, an expert in behavioural ecology at Queen Mary College, University of London, said Britain had seen a rise in an invasive, aggressive wasp, called Dolichovespula media.

'Likewise, hornets are spreading quite a bit - to what extent these two species are responsible for the hospitalisations, I do not know,' he said. 'But certainly if there are more of these stinging insects, then there is more chance that they will contribute to it.'

Dolichovespula media builds relatively small nests in trees and bushes.

Gardeners could easily stumble across the nests and be attacked.

Anyone who is stung and develops a bad reaction should seek immediate medical attention.

Professor Chittka said: 'If you wait too long, you might die.

'All stinging insects are most aggressive near their nests. If you find a nest, get someone professional in.

'If there are wasps in the area and you are eating, look at what you are about to take a bite of. Don't flail your arms at the wasp. Make slow and calm movements.'