The first butterfly of the year is usually a heart-lifting sign of spring. Now it’s arriving in midwinter.
Spotting a lemon-yellow male brimstone jauntily cruising along a hedge filled with the bridal-white flowers of blackthorn is when spring starts for me, and that’s usually in mid-March. This year, I saw one in Surrey on 15 February alongside the blossoming blackthorn and cherry plum. My first butterfly of the year turned up on New Year’s Day: a red admiral, enjoying our extremely mild midwinter.
For those who feel alarm, brimstones are very capable of coming and going in early spring, when fine weather visits for a day and vanishes for a fortnight. I haven’t actually seen a brimstone around my Norfolk home yet, and each year first sightings are often only followed by more a month later.
The key question is whether spring species can adapt, or whether mild extremes disrupt crucial synchronicities between caterpillars and food plants.
The naturalist Matthew Oates has found purple emperor larvae losing their brown winter camouflage and turning green for spring, which usually happens in April. “Hopefully they know what they’re doing,” he says. As long as sallow leaves sprout early too, the caterpillar will remain disguised from predators.
While we wait, in trepidation, for more butterflies, we must cling to Oates’s optimistic motto: never underestimate a caterpillar.
