Carys McMillan from Cheshire Wildlife Trust introduces us to the UK largest brown butterfly, the grayling
The Grayling butterfly is the UK’s largest brown butterfly with a wingspan of around 5-6 cm, and there are six subspecies of grayling butterfly.
What do grayling butterflies look like?
The undersides of the grayling’s wings are mottled brown and this colouring enables it to blend into landing spots of bare earth, tree bark, stones and sand.
When resting the wings are generally closed, exposing this underside colouring. This closed wing position allows the grayling to angle their wings according to the sun’s rays.
Differing angles allow the grayling to regulate its body temperature from the heat of the sun and to minimise shadows which reduces predation.
When in flight and the wings are open, graylings have a range of orange and brown bands in their wings as well as a large eye spot against a cream background.
The grayling can be identified through its swooping flight and repetitively landing and taking off. It is most common to see males with females generally only being seen when egg laying.
How long do grayling butterflies live for?
A grayling has four life stages, with eggs hatching in August. The larvae grow until the following June where they pupate and then around July the following year, adult graylings emerge.
Where do grayling butterflies live?
Although they are found in various habitats across Europe and Britain, they mainly inhabit coastal areas with easy access to the sun.
The grayling butterfly has its adult phase during the British summer months of July through to September and can be found in coastal habitats which include dunes, saltmarsh and cliffs.
There are occasionally colonies found on dry heathland and open woodland, where the habitat areas are well drained with open and bare ground allowing for the graylings unique basking behaviour.
One subspecies, the smallest of the graylings, has colonies on the Great Orme in North Wales, where they are often found to emerge slightly earlier in the summer than other subspecies.
This butterfly is normally found in colonies that range from fifty through to thousands of individuals with only one generation a year populating the colonies. The adults are rarely seen away from breeding areas. In the UK it is rare to see colonies this large with data records stating sightings of 2-29 individuals to be most common.
What do grayling butterflies eat?
Graylings feed on a variety of plants depending on whether they are in heathland or coastal locations as well as what stage of their life cycle they are at. The caterpillars feed on grasses such as sheep’s fescue, bristle bent, early hair grass and marram grass. While the adults are nectar feeders, feeding on plants such as bramble, heather, thistles, red clover and sea holly.
Graylings do not feed very often but are especially attracted to tree sap, which aids their ability to conceal themselves while feeding.
What threats do graylings face?
Grayling populations are declining, and although not globally endangered, they are a priority in butterfly conservation in the UK. It has been noted that graylings have declined by around 60% since the 1970’s due to habitat loss along our coastlines in Britain and are now listed as endangered on the Butterfly Conservation ‘Red List’.
Changes at coastal habitats from human-built features has caused increased growth of grasses and other vegetation on sand dunes. This has reduced the amount of bare sand available, which is the graylings preferred habitat.
Habitat maintenance work such as scrub control (the cutting back and clearing of vegetation) will be essential in reducing the decline in grayling population and providing them with a suitable environement.
Find out more about butterflies
Check out our comprehensive expert guide to British butterflies and the best plants for pollinators.
Carys McMillan is from Cheshire Wildlife Trust
The Wildlife Trusts are making the world wilder and helping to ensure that nature is part of everyone’s lives. We are a grassroots movement of 46 charities with more than 900,000 members and 38,000 volunteers. No matter where you are in Britain, there is a Wildlife Trust inspiring people and saving, protecting, and standing up for the natural world. With the support of our members, we care for and restore special places for nature on land and run marine conservation projects and collect vital data on the state of our seas. Every Wildlife Trust works within its local community to inspire people to create a wilder future – from advising thousands of landowners on how to manage their land to benefit wildlife, to connecting hundreds of thousands of school children with nature every year