The Painted Lady invasion 2009

(adapted from an email from Tom Brereton, Butterfly Conservation)

There was a phenomenal breeding season in the Atlas Mountains in north Africa due to winter rain, with instances of 150,000 pupae in a single field.

 

These started to disperse north north en masse across the Mediterranean from February, with small numbers beginning to reach here in April.

 

The African butterflies bred in Southern Europe from February onwards, initiating pulses of northerly migration across the whole of Europe from February onwards and with arrivals in Northern France, Germany and the Netherlands around 20 May.

 

'Stable isotope' work confirms that they those sampled are from the Atlas Mountains.

 

The first substantial arrival in the UK was on 21 May with 100 at Portland Bill, Dorset.

 

The big NW movement occurred 24/25 May when at a guess 10-50 million arrived in the UK, mainly fresh individuals (those that have bred in southern Europe) plus first generation faded African insects. Big counts all over southern Britain (~50,000 counted), especially East Anglia. It was classic weather conditions for a large arrival over the May Bank Holiday - low pressure over Northern France feeding warmer air to Southern/Eastern England. Warm, sunny with easterly winds over Eastern Britain allowing butterflies to migrate strongly NW with a favourable tail wind.

 

Some have started to settle to breed - eg in Cornwall., SW England

 

Also involved in the migration are (much fewer) Large Whites, Red Admirals, Clouded Yellows and Silver Y's

 

More are expected - Thursday 28 and Friday 29 May look good for another immigration!

 

Then we will have the offspring of this brood in July and August, so there should be huge numbers around - I wouldn't like to be a thistle (the foodplant) in August!

 

This is a global phenomena - with a major movement from Mexico into California happening in mid May.

The Painted Lady in Sussex - Colin Pratt

The Painted Lady (V. cardui) has been recorded in Sussex since the very middle of the 19th century. During that era it sometimes flew "in the greatest profusion in clover and lucerne fields, especially near the coast", but the Victorians recorded few details. Nonetheless it was said that "The spring of 1906 was notorious for the absence of this species, but on the morning of June 3rd of that year hosts suddenly appeared on our south coasts. The banks over Holywell (Eastbourne) were at this time covered with the yellow blossoms of the horseshoe vetch (Hippocrepis comosa), and the butterflies were feeding at them in thousands; a similar state of affairs existed all along the downs so far as I was able to follow them".

During advantageous seasons after 1906 this butterfly could sometimes be seen in hundreds at clover - but this was to be the last sighting of thousands for approaching a century.

In 1996 there were a whole series of large migrations to Sussex, and two of these waves were of a sensational size. The first worthwhile influx of immigrants arrived here during the late afternoon, evening, and night, of May 30th, when significant landfalls were made all along our coast. This migration was accompanied by a few Red Admiral and an even greater swarm of Silver Y, all pushing towards the north-north-west. Within a few hours the bulk of the foreigners had swept across the whole county and pushed further inland. These butterflies were almost all small, faded, and worn, and unusually prone to sunning themselves on the ground.

Further lesser and more localised waves landed over following days, this culminating in further large influxes in early June, but all were dwarfed by a gigantic wave of Painted Lady which first made landfall during the afternoon and night of August 2nd. These insects were accompanied by more hordes of Silver Y and the slim-winged Pyralid moth N. noctuella.

Numbers generally fell back to normal during the first half of September, the species finally disappearing in most places towards the end of the same month, although the very last was seen at Pulborough on November 6th. A few of the late May flight were observed laying eggs but, as is generally the case in Sussex, what little results of local breeding there were, all pushed off northwards.

It’s too early to tell just how 2009 will compare with 1996. If that invasion is a template - and so far it has been - then we have more great arrivals to come, although there will be only a little local breeding. What is certain is that these two seasons will be the foremost in Sussex for this magnificent butterfly since 1906.

Detailed observations on the 1996 migrations to Sussex have been published with full individual attribution, much of the information being kindly supplied by members of Butterfly Conservation. I am collating all information on the current migration. Please continue to contribute sightings via this web site, and please e-mail me with your significant sightings on colin.pratt@talk21.com.

 All of the above information has been extracted from “A Revised History of the Butterflies & Moths of Sussex”, where the references and much more information can be found.

Photos: Dave Mitchell