Dragonflies may have hovered and hunted across the planet for the last 325m years, but their modern relatives are staring extinction in the face. Experts warn that one-third of British species are now under threat, a plight that today sees the opening of the UK's first ever dragonfly centre to celebrate and protect one of the country's most fascinating insects.

Located at Wicken Fen nature reserve in Cambridgeshire, the new centre hopes to reverse the decline of the 42 species found regularly in the UK. Conservationists blame the decline on the loss of wetlands, and pesticides and insecticides drifting from farmland.

Springwatch presenter Chris Packham, who opened the centre today, said: "The loss of wetland habitat throughout the UK is having a massive impact on the long-term survival prospects for many dragonfly species." He warned that three British species have already become extinct since the 1960s.

Dragonflies spend much of their lives underwater as larva "nymphs", and when the winged adult finally emerges its flying lifetime is comparatively short, ranging from just weeks for small species to a few years for the largest. They are a key indicator of water quality and a valuable natural predator of mosquitoes and midges.

Some British species are faring worse than others. White-faced darters have seen a signifcant loss and drying out of the bog pools where they live, while the Norfolk hawker's limited distribution - mostly in the Norfolk Broads - has left it vulnerable to sea level rises and salt water infiltration.

As well as pressure from the historic loss of East Anglian fens, many of which have been drained and converted to farmland, British dragonflies and their prey are at risk from insecticides and pesticides. Vicky Kindemba, freshwater officer at conservation charity Buglife, said: "Different chemicals affect invertebates differently, but one we know about is permethrin - used to treat wood and animals to remove fleas and woodworm - which can affect dragonflies when it finds its way into the water course." Chemicals reaching rivers and streams from agricultural run-off can disrupt dragonfly breeding patterns - reducing the number of eggs, for example.

There are signs that increasingly conservation-conscious farmers are aware of the problem. David Felce, who runs Midloe Grange Farm near the site of the new dragonfly centre, said: "We have several types of dragonfly on the farm, including blue emperors and brown hawkers, which we've protected by building grass buffer zones near our seven ponds and water courses. As well as acting as a failsafe to keep insecticides away from dragonflies and other insects, the grass is a habitat for wildlife in its own right."

Dragonflies are doing better this year compared to 2008, according to anecdotal evidence from naturalists at the British Dragonfly Society. "We think it's due to the sustained wet weather during late spring and early summer last year," said Katharine Parkes, a spokesperson for the society. "This year, although we've still had wet weather, it's been showery rather than sustained, and dragonflies are very good at making the most of sunny intervals."

However, long-term records are required to establish an accurate picture of dragonfly health, and the data collected by naturalists from 1986 to 2005 shows a third of British species are now classified as endangered, vulnerable or near-threatened under official Red List criteria.

Wicken Fen, where the dragonfly centre opened today, is one of the few bright spots for dragonflies and home to 21 of Britain's species. Stuart Warrington, the National Trust's Nature Conservation Advisor for the East of England, said: "Dragonflies symbolise the importance of Wicken Fen and our ambitious project to create a 22 square mile nature reserve. Work to develop good quality habitats for dragonflies, such as clean ditches and ponds, has led to successful breeding of all the species found at Wicken and on the land surrounding the fen."

The new centre, staffed by volunteers, will give visitors access to educational displays, advanced courses on species identification and guided "safaris" to see the fen's darting inhabitants, from the emperor dragonfly to the hairy dragonfly.

Dragonflies: fast facts

• There are more species in the dragonfly family than there are species of mammals

• The wings of a dragonfly beat at up to 35 times a second

• The insects can fly forwards and backwards at up to 18mph

• The eyes of a dragonfly cover a field of vision close to 360°

• The largest species have been known to fly across the Atlantic Ocean

• Dragonflies don't sting humans

• This article was amended on 28 July 2009. Due to editing changes, the original said that the dragonfly family "has more species than any other mammal". This has been corrected.