A small tortoiseshell butterfly rests from the dizzying randomness of flight and alights on a hedge. It’s a sunny noontime and the insect flexes, absorbing solar energy, keeping wing patterns moving to ensure its profile is never still enough to be identified in any bird’s-eye view. The hedge has been flailed, its branch ends shattered and raw, the result of savage violence that makes the small tortoiseshell appear so vulnerable, like a child on a highway.

Butterflies are not as delicate as they look. This one has survived the winter, roused from torpor by a warm spell only to be blasted by chill winds and having to retreat again into the half-death of hibernation. Predation from mice (in sheds) or great tits (in tree holes) can make hibernating deadly.

Wings with bold orange, black and white markings edged with blue dots on top for intimidating flight, and dead leaf camouflage beneath for invisibility – the small tortoiseshells have adapted to predators well. But this has not saved them from Sturmia bella, a fly that lays its eggs on nettles, their main food plant; the spiny fetish caterpillar ingests the eggs, which hatch and feed on juices inside their host until it pupates, dies and the flies emerge. The small tortoiseshell population has crashed by 75% since 1976 – last year was its worst – though the fly was not recorded in Britain before 1999. There will be other contributing factors such as climate change, insecticides and other chemical pollution.

The small tortoiseshell, Aglais urticae, gets the second part of its scientific name from Urtica, the stinging nettles that support two or three butterfly generations a year; big clumps in full sun are best, but so many nettle patches have been cleared and sprayed. Aglais are the brush-footed butterflies – which include the peacock butterflies also bursting through April sunlight – so essential for pollinating.

As the blackthorn winter – the white blossom pulse at the end of March/beginning of April – fades, flowers such as dandelion, ground ivy and celandine receive the attention of butterflies that, despite the hardships they’ve endured, look so vivid of colour and vital of movement. Let’s hope this is a better year for them.

