Coastal locations are excellent habitats for butterflies in general explains Matthew Oates, the National Trust’s butterfly specialist, because areas such as sand dunes, downs, cliffs and grasslands are often inaccessible.
The coast also tends to be sunnier and warmer than it is inland and the common blue loves warmth – the hotter the better according to Mr Oates. It also provides perfect growing conditions for bird’s-foot trefoil, the caterpillar’s food plant.
To help locate any remaining common blue colonies on the coast, Butterfly Conservation and the National Trust are encouraging people to record any sightings during their summer seaside holiday. It could be critical in establishing the importance of coastal sites for these butterflies.
It’s an ideal partnership as the National Trust protects 775 miles of UK coastline and is currently celebrating 50 years of the Neptune Coastline Campaign, their long-running project to protect the coast.
This is a great opportunity to add some useful butterflying to your family seaside holiday
In fact any coastal butterflies spotted should be recorded online as part of this year’s Big Butterfly Count, which is the charity Butterfly Conservation’s annual survey of 18 species of common butterfly and two day-flying moth species. Launched in 2010, it is now the world’s biggest butterfly survey and takes just 15 minutes to complete.
“This is a great opportunity to add some useful butterflying to your family seaside holiday, while you are out on a walk along the coast, or wandering through some sand dunes,” says Oates.
The solution might be as simple as growing bird’s-foot trefoil in your garden, explains Mr Oates, “It’s a low-growing herb with delightful yellow-orange, egg-and-bacon flowers, and withstands a fair amount of mowing.
“The common blue should be a part of everyone’s lives. It should be, could be, and was, a ubiquitous butterfly – and can be again.”
Tips for identifying blue butterflies
The UK has a number of very similar-looking blue butterflies. Luckily Mr Oates has some top tips that will soon have you sorting the chalkhill blue from the holly blue, and the Adonis blue from the common blue. It’s easier than you might think.
Male common blues are bright blue, with a white border along the wing upperside edges; the undersides are grey with orange spots along the outer edges. They live in flowery, grassy places.
Chalkhill blue males are a light, bright "Cambridge blue" in colour. They are common locally, but only on chalk and limestone downs.
The Adonis blue, with its amazing electric blue hues, shouldn’t be out at this time of year, yet. It is a scarce butterfly of short downland turf in southern England only.
Any bright blue butterfly flying high round a bush is likely to be a holly blue, an azure blue butterfly of gardens and scrubland. When they land, you might be able to notice a lack of orange spots on the wing undersides.
In general, at this time of year, most of the bright blue butterflies fluttering among meadows or flowery grassland will be the common blue.
And don’t forget to join in the conversation and share your sightings using #ButterflyCount on social media.