Common Blue butterflies, Polyommatus icarus, are easy to find in grassy spots, especially where the mowers haven’t cut everything to within an inch of its life. You’ll see these insects skipping their way through the air alongside the smaller and duskier-coloured Holly Blue, which emerges earlier in the year. The latter will have completed its first breeding cycle by now, with the adults dying after laying their eggs on holly and Ivy plants and the young emerging in these high summer days.
The Common Blue flies lower to the ground and has orange on the underside of its wings. As with many insects, male Common Blues are more of a show-off than the females, with much brighter blue wings. The females prefer a subtler, more mysterious look. They are a dark brown, often washed with a blue that intensifies towards the body in the centre of the wings.
They live in colonies, gathering in small groups on plant stems at night. Ants are pals of this insect, guarding the caterpillars and chrysalis from predators, often taking the latter into their nests for safekeeping. In return, the larvae secrete a sweet honeydew for the ants to feast on.
This species lays its eggs on members of the pea family, particularly the Common Bird’s-foot Trefoil, Lotus corniculatus. This is a yellow-and-orange flowered plant that grows low on the ground. It’s a hugely important wild flower for insects, so do treasure it if it appears in your garden.
This butterfly has struggled over the past few decades, largely as a result of habitat destruction, including a decline in spaces where Bird’s-foot trefoil can grow. In 2019, it had its best summer in a while thanks to the warmer weather.
But that word “Common” probably lulls us into a false sense of security that all is well with this butterfly — and the other 58 species that live in or visit this country. We claim to like these insects above all others, while often tidying our environment to the extent they have nowhere to live and feed.
This obsession with tidiness will make our lives much more boring if it means that there is no room left for the Common Blue.
Isabel Hardman is assistant editor of The Spectator and author of The Natural Health Service
Have you spotted any Common Blue butterflies recently? Let us know in the comments below.