Williamson Weekly Nature Notes June 10 2009

I first saw these very fast butterflies while walking the Downs at Kingley Vale near Chichester.

That was May 22. The next day I was on farmland at Rotherbridge, just south of Petworth. Painted ladies were again shooting past me at a great rate of knots, almost too fast to see their colours or to get an exact ident. But as there were many more all on the same westerly track there seemed no doubt that every one of them was one of the famous immigrants, and not just a peacock or faded red admiral.

The day after that I was down near Pagham on the coast, and again painted ladies were streaming past all flying west.

Like all other butterfly watchers I have seen mass immigrations like this before. Not every year, but maybe once every decade. What happens is that down in Africa and around the Med., painted ladies have an exceptionally good breeding season.

There are just too many of them for the land around to support. So for the sake of the species as a whole, they are programmed to get on their bikes and go north or west.

Some become so motivated by this urge triggered by a hormone, they hardly stop, but just keep on flying.

So they have been known to end up in Iceland, or the North Cape of Norway. Some probably go on towards the North Pole. This of course is a hopeless quest for breeding space but they just can't switch off that demon hormone.

The very first recorded invasion thought to be of the species was back in 1272. Other big years were 1889, 1903, 1950, 1980, and 1996. Those that decide to call it a day in England are the more sensible butterflies because their eggs will be successful.

They lay these on thistles. Burdock, mallow, and viper's bugloss are sometimes used as the nursery food.

The resulting caterpillars pupate, hatch out as adults in September and go home to Africa with all possible speed.

I think this is one of the prettiest of all butterflies with its big wide orange wings and those black and white speckled patches all over the tips.

Amazing to think that those speeding past so swiftly across our gardens, houses, farms and downs have actually flown 1,500 miles already.

They may rest awhile in your garden for a moment or two. All those I have seen so far were too busy and focussed even to stop for a moment.