Will this be a 'painted lady summer'?

 

This spring was notable for an early influx of migrant painted lady butterflies that arrived here on warm southerly winds, raising hopes that this might be a 'painted lady summer'.

They began to appear in Weardale in substantial numbers towards the end of the heatwave in May but were reported in southern and western counties from mid-April onwards. There has long been speculation that these early arrivals fly here directly from North Africa. The tattered state of the butterfly in the photo above, nectaring on sweet rocket aka dame's violet Hesperis matrionalis in my garden, suggests that it might have had a long and eventful journey.

L. Hugh Newman, whose family ran a butterfly farm in Kent (that supplied Winston Churchill with butterflies for his garden at Chartwell) kept detailed records of their lifespans. Resident breeding species typically had lifespans of less than a month , with the exception of those that overwintered as adults (10-11 months for brimstone, small tortoiseshell, peacock) and found that 30 days was the maximum lifespan of painted ladies. They are known to fly at night and with a favourable wind, they are reckoned to fly about 150km. per day, so it’s just conceivable that some early spring arrivals here might have made the one-way journey directly from North Africa, but there’s no doubt that the true test of whether we are due a ‘painted lady summer’ depends on their breeding success at various locations in continental  Europe, and favourable summer winds.

Most arrive in relays, crossing the Mediterranean to breed in France and Spain first. With their short life cycle - egg to imago in six weeks - their numbers multiply exponentially as they move northwards, a rolling wave of butterflies that reaches our shores in mid- summer.

Spectacular ‘painted lady summers’ are the stuff of lepidopterists’ legends. I recall walking along the coast near Whitby in 1996, surrounded by hundreds of painted ladies settling to feed in flowery cliff-top grassland. That invasion reached Orkney and Shetland. The most recent mass migration that I remember here was in 2009, but size and frequency of such events are subject to favourable winds and clement weather.

 

The end of an epic journey

 We found this dead salmon, on Christmas Eve, in Waskerley beck, a tributory of the river Wear at Wolsingham in Weardale. It had evidently swum upriver from the sea to spawn in shallow gravels and died of exhaustion, old age or disease - or perhaps from all three causes. Patches of fungal disease are clearly evident on its scales. Few salmon make it back to sea after they have spawned.

It would have begun life in the river as an egg, made its way downstream to the North Sea, then spent up to four years in  the sea before returning to its home river to spawn. The end of an epic journey.

Silver Y

This hasn't been a particularly good year for the silver Y moth Autographa gamma numbers in my part of County Durham. In some years many thousands migrate here from the Mediterranean early in the year and by now, after several generations of breeding, the Michaelmas daisies and Buddleia x weyeriana in the garden would be smothered in them. It's only now that a few are appearing on a daily basis, just as the frosts begin. The cool, wet summer may be to blame. 

Silver Y moths are restless insects, never coming to rest while they feed, so it can be difficult to appreciate the beauty of their mottled wings. But after a cold night they are more accommodating, resting head downwards, waiting for the sun to warm them up. Today Martin Wainwright, over at Martin's Moths, has some fascinating information on the way that moths go through their pre-flight warm-up routine.

We found this silver Y early yesterday morning on a dry stone wall high in the Pennines, 400 metres asl on Chapel Fell where the grass was still covered with frost. The mottled wings provide excellent camouflage on a lichen-covered rock and my wife only spotted it because it had begun to shiver, as part of its warm-up.

When we got home we found another that had spent the night on our window, probably attracted to the room light last night and again resting head down. No effective camouflage this time, but from this angle the irregular outline of the dorsal side of the body is evident - all part of the crypsis in profile as well as plan view if the moths land on a suitably matching background.

In a good year there would be vast numbers of silver Y moths on the wing now and Africa Gomez, over at her excellent BugBlog, describes how it has recently been discovered that they are capable of migrating south, all the way to the Mediterranean with a favourable wind, to escape our winters which would kill almost all of them.

You can find another picture of a silver Y feeding here