A medium sized brown butterfly flies up from almost beneath your feet, flutters away from you for a few metres, lands and disappears. The same performance is repeated until you decide to approach slowly and stealthily to discover the identity of this cryptically coloured insect. Despite being certain of where it landed you struggle to locate it until you lock onto the culprit sitting motionless with wings closed amongst the sparse vegetation. It casts no shadow because it has angled itself to face the sun; it shows no obvious markings because it has pulled its wings tightly together to hide a prominent eye spot. It is a grayling butterfly, one of the family of ‘browns’ and a specialist inhabitant of dry, sparsely vegetated heaths and dunes.
Once located you will be able to admire the way nature has decorated this small creature, endowing it with superb camouflage; intricately vermiculated patterning of silver, grey and brown rendering it almost invisible. Then away it flits, perhaps seeing off a rival male or intercepting a passing female hoping to entice her down to mate. Now here is where it can become interesting. If you are very lucky you may witness a rather intimate courtship ritual whereby the male will try to impress his prospective mate with a series of elaborate wing flicks before wrapping his wings around the young lady’s antennae so that they come into contact with his scent scales. Butterfly antennae are very sensitive to smell, so in this way she can be stimulated to mate. Hot stuff! Subsequently, eggs are laid singly on a variety of grasses where the emergent caterpillar will feed under the cover of darkness. Hibernating during the winter safely tucked away in a tussock, the caterpillar will complete its growth and metamorphosis during the following spring.
Here in Norfolk, the grayling has its strongholds along the north and east coasts and the Brecklands. It can also be found on heaths and commons scattered around the county. I’ve even had one turn up in my garden at Sprowston in Norwich, a visitor from nearly Mousehold Heath I suspect. Although the general distribution of the butterfly has changed little over the last century, numbers have declined significantly in recent decades during this millennium. Coastal populations are very vulnerable to salt water inundation so suffer from storms such as we experienced during 2013 and more recently. Inland colonies suffer from fragmentation and poor management of their favoured habitat. The significant decrease in our rabbit population, currently under attack from various diseases, is another factor affecting the suitability of the favoured habitat of bare, sun baked ground. It is therefore very important that we safeguard our heaths and commons and keep them in good condition, encouraging maximum diversity and allowing such vulnerable species to find a niche.
Graylings can be encountered from mid-July to mid-September, so now is an ideal time to get out and look for these enigmatic insects on your local common. Concentrate your efforts on those areas that have bare ground or very short grass and you may be rewarded.
You can play your part in the conservation of the species by making a record of your sighting and emailing it to Norfolk Wildlife Trust. Every record counts and will be greatly appreciated so that the fortunes of this muted toned butterfly with a colourful courtship can be monitored.