LEAVING grass to grow long in gardens can increase butterfly numbers by up to 93%, according to new research.
The study, by the wildlife charity Butterfly Conservation (BC), provides the first scientific evidence that even a patch of long grass in your garden increases butterfly abundance and also attracts a wider range of species.
The findings, published in the journal Science of the Total Environment, offer hope that creating “wild spaces” in gardens may help reverse the decline of the colourful insects.
Researchers analysed butterfly sightings from over 600 UK gardens — including the length and breadth of Scotland — collected by members of the public over six years through BC’s annual Garden Butterfly Survey.
The results show that gardens with long grass recorded a significantly higher number of butterflies and a greater variety of species, than those without.
The biggest benefits were found in urban areas and intensively farmed landscapes. In highly arable areas, gardens with long grass saw up to 93% more butterflies, and those in urban areas saw 18% more.
Gardens make up more than 728,000 hectares in Britain — the equivalent of over a million football pitches. BC suggests that if each had a space allowed to “go a little wild”, it would make a huge difference for butterflies and moths, providing spaces for them to feed, breed and shelter.
While the research specifically studied gardens, the benefits to butterflies of long grass and wild spaces are likely to extend to public green spaces such as parks, school grounds, allotments, and road verges.
Dr Richard Fox, Head of Science at Butterfly Conservation and co-author of the study together with BC scientist Dr Lisbeth Hordley, said: “This study proves for the first time that you see a greater abundance of butterflies in your garden if you have long grass compared to no long grass.
“Also, the fact that you see disproportionately more butterflies and more species of butterflies, the more long grass you have.
“Both of those positive relationships are driven by the group of butterflies whose caterpillars feed on grass. In Scotland these include the Meadow Brown, Ringlet, Small Heath, Speckled Wood, Small Skipper and Large Skipper.
“It suggests that either the butterflies are breeding in that long grass, which is the end goal, or are visiting the garden to check out the long grass as potential breeding habitat.”
The study also found that the presence of flowering ivy in gardens increased the number of certain butterfly species, such as the Holly Blue, Red Admiral and Comma, which use ivy as a breeding habitat or nectar source.
BC hailed the findings as “great news for gardeners and non-gardeners alike”.
The charity is now calling for everyone to create their own Wild Space to help butterflies survive and thrive. Through its Wild Spaces programme, it aims to transform 100,000 areas across the UK to help support butterfly populations.
Dr Fox said: “Nature is in crisis, 80% of butterflies have declined since the 1970s, so we need to take action now to protect them.
“We wanted to be able to give tried and tested gardening advice that will benefit butterflies as we know lots of people want to help.
“The simple act of creating wild spaces by allowing a patch of grass to grow long, or a border edge to go wild is free and easy to do, and can significantly boost butterfly numbers, especially in urban and agricultural settings where they are most under pressure.
“The benefits of each individual wild space are small but, if thousands of people get involved, the boost to butterflies could be huge.
“Whether you have a large garden, a small patch of grass, a community or school space, or a balcony or window box, anyone, anywhere can help.
“We hope that our Wild Spaces programme will inspire people across the UK to take action and help to create a national network of butterfly-friendly habitats.”
