BUTTERFLIES are appearing in the region earlier than at any time since the 1940s, a recent study has revealed.

Entomologists say global warming is the most likely reason behind some species being spotted in Britain as early as mid-January.

Five species - brimstone, small tortoiseshell, red admiral, peacock and comma - now appear an average of 74 days earlier than in the 1940s.

The study, published in British Wildlife magazine, has found that all butterfly species appeared earlier in the 1990s than in the 1940s or 70s. It has also emerged that butterflies are fitting in two breeding periods a year, because they are not hibernating until after October.

The findings back up sightings of rare species in the region that are regarded as the strongest indication yet that global warming is on its way.

Two years ago, four rare dragonflies - one of which is normally found in southern Europe - were spotted on the pond at Rainton Meadows nature reserve, near Houghton-le-Spring, Wearside, the headquarters of Durham Wildflife Trust.

Other rare species were seen near Crook, in Weardale, and stretches of the River Wear, between Chester-le-Street and Witton-le-Wear.

Professor Brian Huntley, who leads a team based at Durham's University's environmental research centre looking into the distribution of butterflies, says it is too early to say if the changes are good or bad.

He said: "We don't know yet if climate change is having a negative effect on butterflies.

"It does matter, though, because it can lead to a mismatch in the timing of certain events. For example, if a plant butterflies rely on for nectar comes out in the spring or autumn, it will miss the flowers if it arrives in January or February."

This latest study is in line with others showing that plants are flowering earlier, grass is growing longer and frogs are spawning earlier.