By Alex Kirby
BBC News Online environment correspondent
British moths are in serious trouble, possibly because of changing climate, a scientist will reveal later this week.
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.
That shows that some of the worst-affected species, moths like the dusky thorn and the hedge rustic, have declined by more than 90%.
Dr Conrad thinks climate change could be responsible. He said: "These species overwinter as eggs, and they don't appear to be surviving the warmer, wetter winters of recent years."
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.
This species, like other lichen feeders, is on the increase, possibly because lower air pollution is encouraging better lichen growth.
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.