By Alex Kirby BBC News Online environment correspondent

The hedge rustic: Two-thirds of UK moths show some decline

Dr Kelvin Conrad of Rothamsted Research will tell the British Association's annual meeting in Exeter that about two-thirds of UK moths are declining.

He says about a fifth of all British moths are losing numbers sharply enough to cause conservationists concern.

Moths are seen as a good indicator of the general health of the environment, because they occupy most habitats.

Rothamsted Research, north of London, is the UK's largest agricultural research centre.

Dr Conrad will be presenting data from a 35-year study of moths caught in Rothamsted's nationwide network of light traps to the BA Festival of Science on 9 September.

Winter woes

That shows that some of the worst-affected species, moths like the dusky thorn and the hedge rustic, have declined by more than 90%.

Scarce footman: Some species are doing better

He told the BBC: "About two-thirds of species are declining, and about 20% of all species are declining quite sharply - enough to give us some real concern.

"And you have to remember that these are common moths - that's what our traps can catch. They are the equivalent of the sparrows and starlings, and the alarm that has been caused over their decline in recent years."

Swings and roundabouts

But some species are thriving - numbers of the scarce footman caught in the traps, for example, have increased more than twentyfold.

The moth decline mirrors that of UK butterflies

A study published this year in the journal Science showed that 71% of UK butterfly species had fallen over the last 20 years.

The researchers in this study blamed habitat destruction and climate change for the observed decline.

The Rothamsted light-trap network usually catches around 600 different moth species in any one year, and has caught 900 of the UK's 2,600 different moths in its time.

The network started in 1965, but some data from Rothamsted farm goes back to 1933.