Largest butterfly migration for decades

Largest butterfly migration for decades - media release

Hundreds of thousands of Painted Lady butterflies (Vanessa cardui) reached the UK this week after a flying over a thousand miles from Morocco.  In a mass migration, the scale of which has not been seen for years, these butterflies can be spotted in almost every field and congregating in large numbers on butterfly nectar plants.  The Painted Lady is a pale orange-brown butterfly and is characterized by an extremely swift flight.  It is the

 mostly widely-distributed butterfly in the world being found on all five continents.

The migration has been tracked on butterfly and birdwatching forums as it moved north through Spain and France earlier in the year.  The main numbers reached the Wales just before the weekend and judging by reports there are more on the way.  Butterflies often congregate on hill tops and I counted over forty butterflies in the air at the same time near the Blaenplwyf aerial mask Aberystwyth.  There were over 400 butterflies on a half mile stretch of road there; something rarely seen nowadays.   Mostly the migration will be seen as the odd butterfly passing over a field every minute or so but this is happening all across the 

UK.  On the actual migration front, huge surges in numbers can been observed.  In one day in Norfolk last week, an astonishing 18,000 butterflies were recorded passing through.  Maybe once, just for once, we can catch a glimpse of what the countryside was like a century ago.  

Some people might assume that it is the sunny weather bringing the butterflies out but in this case it is just a coincidence.  The real reason for the migration lies in 

the fre

ak rains experienced last winter in the Atlas Mountains in Morocco.  The resulting lush vegetation provided fodder for huge nu

mbers of caterpillars in January and February.  By the time these turned to adult butterflies, the food plants had all but disappeared spurring them to migrate to greener fields abroad.  In an interesting parallel, a similar mass migration of Painted Ladies is occurring in the United States, with the butterflies starting in the arid south-

western deserts and now moving north through the States.  Again, unusually heavy winter rains in the desert regions started the population explosion.

The Painted Ladies will lay their eggs on thistles in the UK which will be good news for farmers.  A few will lay on related sunflowers and possibly on some Mallow relatives in the garden.  These will produce further generations of butterflies, a few of which will make the return journey back to Morocco and Spain later on in the season.  In the meantime, we should enjoy a bumper summer season of butterflies.