At least twice in recent weeks I've turned on the radio and heard James Naughtie wiffling about butterflies. It makes a change from the usual rout, and it's nice to imagine harried listeners taking a moment to spot a cabbage white flit past. The story goes that this year has brought the earliest emergence of the orange-tip butterfly in a hundred years, as a result of the unusually hot spring.

In the foreword to a set of interviews, Nabokov described his two pleasures as "the most intense known to man: writing and butterfly hunting". At the museum in St Petersburg that was once his house, you can see his collections of the creatures, pinned into frames. On the walls are pictures of him as an old man in Switzerland, stalking the mountains in shorts and wielding a giant white net.

There has always been something incongruous about Nabokov and his love of butterflies - a brain so aggressively powerful choosing to spend so much of its energy on these ephemeral, pretty things that seem to die before they should. But he was very good at it, discovering species (the genus Nabokovia is named after him) and contributing to academic journals. To the horror of diehard fans, he once admitted that, had there not been a revolution in Russia, he would probably have devoted his life to lepidopterology "and never written any novels at all".

Butterfly comes from the Old English buttorfleoge, which links back to the Dutch boterschijte - a reference, it seems, to butterfly excrement's resemblance to butter, hence "butter-shit", and then the more acceptable "butterfly". An alternative explanation is that butterflies, or witches in disguise as butterflies, stole butter.

The ancient languages were a little more poetic. In both ancient Greek - psyche - and Latin - papilio, which bred the French papillon - the word was associated with the soul of a dead person. In Spanish, it's mariposa, a reference to the Virgin Mary coming to rest. For sheer fun to say, the Germans win (Schmetterling), but it's the Yiddish that stole my heart: zomerfeygele, literally "summer bird". That's how we should celebrate them, I think, not like Nabokov with a net, but watching these birds of colour in their freedom, flying.