Watch a report by ITV News Anglia's Stuart Leithes.
Hand-written notes made by a naturalist who was a friend of Charles Darwin are being used to try to halt butterfly decline.
Leonard Jenyns, who lived in Cambridgeshire in the 19th Century, recorded local wildlife in detailed notebooks.
Now, his two-century-old notes are being used for future conservation efforts, in hopes of reversing butterfly population decline.
They are now centre stage of a new exhibition called "Butterflies Through Time" at the Museum of Zoology in Cambridge.
The exhibition gives visitors the chance to see rare butterflies usually held behind the scenes in the museum's storerooms.
Along with thirteen species of butterflies on show from the last two hundred years, the exhibition also looks at the current research and conservation being undertaken to protect them.
Working alongside the Wildlife Trust, the information from the museum's specimens along with Jenyns' notebooks is helping to guide habitat restoration work on nature reserves.
Dr Ed Turner, Curator of Insects at the Museum of Zoology said:
"We've lost such huge expanses of wetlands, fenland habitats, so roughly in the UK we think about 75 per cent of UK butterfly species based on modern records, have declined in abundance since the 1970s,.
"What we've show in our work in the museum is that this is the tip of the iceberg really and something that has been happening for the last 150 years."
Among the speciments included in the exhibition is the Swallowtail Butterfly, which disappeared from Cambridgeshire in the 1950s when its fenland habitat was drained for farmland.
It's now only found around the Norfolk Broads.
Dr Gwen Hitchcock is a Conservationist for the Wildlife Trust told ITV News Anglia that there is a lot of potential to do some good now.
"It highlights the importance of biological recording and how, by working together, we can ensure a future for our wildlife."
"It's really exciting with this exhibition to see how past records can help with the current, and future, conservation of these beautiful and important species.
It highlights the importance of biological recording and how, by working together, we can ensure a future for our wildlife."
Dr Turner said: "Butterflies are among the most beautiful and popular groups of animals.
This exhibition highlights the wonderful variety of species found locally, but also their fragility and need for conservation".