The number of people admitted to hospital due to wasp, bee and hornet stings has more than doubled, it has been disclosed.

Some 843 people were admitted for medical care in 2004-05 compared with 369 in the financial year 2003-04, according to a response to a written parliamentary question that appeared in Hansard yesterday.

In addition, eight people died from insect stings in 2004; in 2003 there were three deaths. Professor Lars Chittka, an expert in behavioural ecology at Queen Mary, University of London, said millions of bumblebees shipped to Britain for use in commercial glasshouses could be partly responsible for the rise in stings. He said: "The one increase we have seen is in bumblebees used to pollinate plants such as tomatoes and strawberries, which are now grown all year round in glasshouses in Britain.

"Millions of colonies are shipped in for this and they can be very aggressive close to their nests, so workers in the glasshouses would be more at risk of stings. Apart from this though we are not seeing any major increases of numbers elsewhere."

The number of stings is also closely linked to the hot weather, Professor Chittka said. "At the end of the summer is the most likely time for an unpleasant encounter. Their natural resources decline and you will find bees and wasps looking for food at our barbecues and in our ice creams, so they are more obvious to us then."

According to NHS Direct advice, anyone bitten by a wasp, bee or hornet should carefully remove the sting, wash the area with soap and water and cover it with a cold flannel. Raise the area that has been stung to prevent swelling, use a spray containing local anaesthetic or antihistamine to stop the itching and take painkillers if it is painful.