Is there anything I can do to help Spiky Yellow Woodlice?
Priority Species Spotlight: Spiky Yellow Woodlouse
Discover how we’re helping to bring one of the UK’s most threatened invertebrates back from the brink.
Conservation StatusCritically Endangered(IUCN Red List)
Population StatusDeclining
Main ThreatsHabitat loss and fragmentation, plant diseases, climate change
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Get to know Spiky Yellow Woodlice
Rising up out of the South Atlantic Ocean, about 1,200 miles (1,900 km) from the coast of Africa, the UK Overseas Territory of St Helena is one of the world’s most remote islands. So remote in fact, that Napoleon was exiled here after his defeat at the Battle of Waterloo.
Cut off from the rest of the world, life on St Helena has evolved in weird and wonderful ways seen nowhere else on Earth. From Blushing Snails to tree daisies, the island is home to hundreds of unique, endemic species – including the aptly named Spiky Yellow Woodlouse.
As names go, this one certainly does what it says on the tin: these little critters are spiky, and they’re yellow. But they also have a very unexpected party trick – when the sun goes down, they glow under UV light!
Unlike the woodlice we’re used to seeing in our gardens, which lurk under logs and scuttle beneath stones, Spiky Yellow Woodlice have a head for heights and spend their lives clambering about on the leaves of tree ferns, and trees like the Black Cabbage Tree, in St Helena’s cloud forests.
Did you know?
Spiky Yellow Woodlice might look like insects, but they’re actually crustaceans and are more closely related to lobsters and crabs than insects, like beetles.
Why are Spiky Yellow Woodlice in trouble?
The Spiky Yellow Woodlouse’s problems began all the way back in 1502, when humans first discovered St Helena. The Portuguese explorers who settled here brought goats along with them, as well as furry stowaways in the form of rats and mice, and these hungry new inhabitants started munching their way through the island’s plant and animal life.
Then, when the British colonised the island in 1659, they began chopping down trees for timber and fuel, eventually clearing huge areas of native forest to make way for invasive plants, such as New Zealand flax, which was used to make rope for export.
Fast forward to today, and St Helena’s once vast cloud forest is now fragmented into a few precious pockets scattered across the island. In total, just 16 hectares of cloud forest remain, compared to about 600 hectares before humans began living on the island, but these fragments are now all legally protected, in the Peaks National Park.
Unfortunately for Spiky Yellow Woodlice, climate change is also threatening their habitat, as droughts and extreme weather events become more common. And now plant diseases affecting native trees, including the Black Cabbage Tree, are piling yet more pressure on what remains of their forest home.
Many of St Helena’s species have been lost completely – including seven of the eight unique birds that once lived here – and although the Spiky Yellow Woodlouse is clinging on, it’s now classed as Critically Endangered. No more than 500 woodlice are thought to remain, in about 12 isolated colonies.
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How is the RSPB helping Spiky Yellow Woodlice?
The RSPB has been involved in helping Spiky Yellow Woodlice since 2016, supporting our local partners – the St Helena National Trust and St Helena Government – as well as local people, to save these charismatic crustaceans and restore the cloud forests they call home.
To restore the forest, we’ve formed an even wider partnership including the water utilities company on the island (Connect Saint Helena) and international partners. Together, we’re clearing areas of invasive species and growing native plants – many of which are unique and threatened – that can be used to create new areas of cloud forest. Thanks to funding from the Foreign, Commonwealth & Development Office (FCDO), we’ve planted more than 40,000 plants from 17 different species into restoration sites and living gene banks over the last four years.
And the brilliant news is that we’re already seeing wildlife benefit from the new corridors of habitat that have been created to link existing patches of cloud forest – in 2022, surveys showed that Spiky Yellow Woodlice were using a corridor created just four years before.
As well as supporting wildlife, St Helena’s cloud forest also plays a vital role in capturing water from the clouds that cloak the island’s steep central mountain ridge, providing the majority of the island’s fresh water supply. So, work to restore the forest will not only benefit nature but also help to boost the local community’s water security in the face of climate change.
In September 2025, we celebrated the news that we’ve won a UK Government Darwin Plus-funded grant that will help to fund our work on St Helena for the next three years. Thanks to this funding we’ll be able to continue supporting our partners to restore St Helena’s cloud forest, as well as carry our research to help us understand more about the lives of Spiky Yellow Woodlice and other threatened cloud forest invertebrates.
Taking species on a journey to recovery
Helping species to reach a healthy conservation status is a journey. Each journey is tailored to the species in question, but shares four stages:
1. DiagnosisIdentifying there's a problem, and researching to find out what's causing it
2. Testing solutionsDeveloping practical solutions and trialling them to make sure they work
3. RecoveryProviding these solutions across the whole range of the species
4. Long-term legacyReaching improved conservation status and securing a long-term legacy for the species’ recovery
Recovery stage
Our work to help Spiky Yellow Woodlice is at the Recovery stage of the species recovery curve, because we know what needs to be done to help them and work is happening to deliver these solutions. However, this doesn’t necessarily reflect an increase in the numbers of woodlice just yet – trees take time to grow and so the full fruits of our labour to restore their cloud forest home will take time to be realised. But we’ll continue to do all we can to ensure these marvellous minibeasts survive and thrive.
Find out more
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Thank you!
We’d like to say a big thank you to the community of St Helena who have enthusiastically supported conservation work to protect the island’s unique and special species.
Thanks also go to our members, supporters and partners, including the St Helena Government, St Helena National Trust and Connect Saint Helena, as well as our funders the Foreign, Commonwealth & Development Office (FCDO) and Darwin Plus, who have made this work possible.