A survey to monitor UK dragonflies is launched today at the Natural History Museum.
The British Dragonfly Society's 5-year survey will try to get a better picture of UK dragonflies, more than a third of which are in decline, say the society.
Their distribution has changed greatly in the last few decades due to habitat loss, pollution and climate change.
The results of this survey will help scientists conserve threatened species better and help understand how climate change is impacting all British dragonflies.
'The British Dragonfly Society is encouraging naturalists to get involved in the survey because their dragonfly records will be vital in piecing together this important information,' says Steve Brooks, freshwater insect expert at the Museum.
Dragonflies belong to the Order of insects called Odonata, which also includes damselflies, so people should look out for those too.
Some experts think dragonflies should be used to help monitor environmental changes resulting from climate change as the insects are sensitive to temperature changes.
Large red damselfly © Y Da Silva
Dragonflies lay their eggs in water and the water temperature affects the rate that their larvae develop. The air temperature is crucial too, as dragonflies need moderately warm air to be able to fly.
Steve Brooks and colleagues reported on the value of having dragonflies as an official key climate indicator group in the journal British Wildlife earlier this year.
'The distribution and abundance of many of Britain's dragonflies has changed significantly in the last two decades in response to climate change and other changes in the environment,' says Brooks.
'Data from the new survey will tell us whether the rate of these changes is continuing to increase.'
Dragonflies need warmth to survive, which is a reason why there are more species in tropical countries. There are, however, 39 dragonfly species in the UK including three specially adapted to living in colder conditions and found only in Scotland.
As the climate has become warmer, many species have expanded their range further north. The migrant hawker, Aeshna mixta, and the emperor dragonfly, Anax imperator, made their first appearance in Ireland in 2001. And the ruddy darter, Sympetrum sanguineum, and hairy dragonfly, Brachytron pratense, have appeared in northwest England for the first time in the last few years.
The small red-eyed damselfly, Erythromma viridulum (pictured at the top of the page), first appeared in England in 1999 and since then has spread across much of southern England. It arrived here naturally from Europe in response to global warming and is the first species of dragonfly to have colonised this country since people started recording dragonflies 300 years ago.
Dragonflies can be great for the garden as they eat mosquitoes, flies, midges and other insect pests. They are often found near ponds, lakes and other wetlands as they spend most of their life-cycle in the aquatic larval stage. This can last from two months to as much as five years in some larger species. The flying adults live for up to four months.
Dragonfly adults can be very striking in their colour and when seen hovering and darting about. You can tell the difference between damselflies and dragonflies by looking at the position of the wings when they are at rest - dragonflies hold their wings wide open, whereas damselflies hold their wings closed or slightly open over the abdomen.
With a third of the dragonfly species in decline in the UK, people's sightings will be an important contribution to this survey.