New eco-friendly ways of farming could be causing a steep rise in the UK's wasp populations, an expert has said.
Dr Archer measured a rise in wasps in 2002
Michael Archer, a retired lecturer in animal behaviour and ecology, made the claim after analysing wasps caught across the country in 2002.
He found that numbers of common and German wasps had increased to levels not seen for more than 20 years.
Wasp numbers had been falling since 1980, probably due in part to intensive pesticide use and hedgerow removal.
"In 2002, some data that was taken at suction traps suggested the number of wasps were at levels found previous to 1980," Dr Archer, who has been studying wasps for over 40 years, told the BBC Radio 4's Farming Today programme.
"The reason I put forward for wasp numbers dropping off was intensive agriculture, particularly the increased use of pesticides.
"Now in the last few years, government agri-environmental schemes have been trying to encourage wildlife in the countryside and perhaps the increase in wasps in 2002 is an indication that these schemes might be working."
The countryside stewardship scheme offers farmers incentives to set aside strips of arable farmland for diverse vegetation, encouraging insects.
Dr Archer said the rise in wasp populations for 2002 was positive if it was an indication of a more general recovery of wildlife in the British countryside.
"Wasps have a bad reputation. But it's not a bad thing having more insects, because they are essential for birds," the former York St John College lecturer said.
"You need more insects to have a bird population. We are very concerned about our farmland birds, which have suffered greatly."
Farmer and wasp control specialist Richard Burt said that eco-friendly farming might be partially responsible for the rise, but it was not the whole story.
He commented that this summer had been marked by more insects in general, including aphids and orange blossom midges - small, orange flies that winter in the soil of wheat fields.
"I don't think farming is entirely to blame for a plague of wasps. This summer we have seen a situation that has created a lot of pests," Mr Burt said.
"We saw early summer being very attractive for blossom set. We saw moist soil conditions which allowed certain insect types to breed freely. Therefore, population numbers are at a peak," he said.