Surviving winter is the ultimate challenge for the 60 butterfly species that make their living in Britain.
Different species use different tactics. The riskiest, and therefore chosen by the fewest, is to hibernate as adult butterflies. Only five species choose this path and they favour cryptic undersides – so they disappear from view when their wings are closed.
The jagged profile of the comma makes it resemble a dead leaf. Peacocks have virtually black undersides and look for dark places – caves, wood piles, sheds. If disturbed by a potential predator mid-sleep, they flash their wings to reveal fearsome bird-like eyes that, hopefully, will repel a hungry mouse.
Other species take on winter in a delicate chrysalis. These can be surprisingly robust – the swallowtail’s chrysalis can survive being underwater in winter floods.
If I was a butterfly, I’d spend winter as an egg – tiny, tough and often glued firmly to bare tree branches. Now is the best time to find new populations of the elusive brown hairstreak, when their minuscule golf ball-like eggs are visible on bare blackthorn branches.
Surprisingly, though, most butterflies endure winter in fleshy caterpillar form. A dusting of frost or snow helps disguise purple emperor caterpillars – motionless on sallow branches – from their greatest peril: ravenous great tits.
Two species cope with winter another way: by not being here. Every autumn, painted ladies and clouded yellows fly south through Europe, chasing the sun. Many of us wish we could do the same.
