Bird migration is much studied but not yet fully understood. Dragonflies also fly long distances but even more remarkable is the fact that seemingly flimsy butterflies undertake journeys of hundreds, even thousands of miles to disperse.

Centuries ago it was quite common to see vast clouds of white butterflies coming in from the sea on our south and east coasts. Such migrations are now few and far between but still occur every few years.

One remarkable event took place in May 2009 when billions of painted lady butterflies flew in. The ‘invasion’ was made possible when heavy rains stimulated their caterpillar foodplant in Morocco. Foodplant exhausted, the ladies were compelled to set off northwards via Spain then across the English channel to seek fresh foliage.

I was enjoying a picnic by the lake in Claremont Gardens at Whitsun when at about 1pm, I spotted a painted lady flying fast in front of me at head height. Minutes later another flashed by, then another followed by one about every minute, wings beating in a programmed rapid unwavering rhythm as they sped northwards to spread throughout the country.

The influx lasted for a few weeks, with our gardens and parks graced by the painted ladies poised on every flowerhead. The butterflies bred here producing another generation in late summer, many of which flew southwards, this time at some height, mainly detected on radar on their return migration to Morocco. I wonder if 2016 will bring us any migrant butterfly species such as whites, painted ladies or clouded yellows?