Apparently the Painted Lady migration is happening in USA as well. It only happens once or twice a decade or so I have been told and its happening now. Here is a link:
http://www.npr.org/templates/story/stor ... Id=4563896
I have a few more links:
PDF Document on Migration in Europe:
http://www.museum.state.il.us/ismdepts/ ... rticle.pdf
Here is a blog on the migration across Europe that might be of interest to people:
http://vismig.blogspot.com/
Extract I found interesting from blog (note the number of pupae found):
In haste....Painted Lady Summary
· Phenomenal breeding season in the Atlas Mountains due to winter rain – eg estimated 150,000 pupae in a single field.
· Mass dispersal north across Mediterranean from February.
· UK: Small numbers faded individuals reached UK April-mid May - widely scattered in one's and two's.
· Breeding of African winter brood in Southern Europe Feb onwards.
· Mainland Europe– waves/pulses of northerly migration across the whole of Europe from February onwards – Spain, France, Italy, Mediterranean Islands etc, in the preceding days and weeks, with arrivals in Northern France, Germany and the Netherlands the middle of last week.
· Stable isotope work confirms that they those sampled are from the Atlas Mountains.
· UK: 21st May first substantial arrival detected in the UK, at Portland Bill (~100).
· The big NW movement occurred 24/25 May when at a guess 10-50 million arrived, 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.
· Small numbers in Northern England but no large arrivals yet….should be any day
· Some starting to settle to breed – eg in Cornwall., SW England
· Also involved in the migration Large Whites, Red Admirals, Clouded Yellows and Silver Y's
· Classic weather conditions for a large arrival over the 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.
· More are expected – Thursday and Friday this week looks 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 in August!
· This is a global phenomena - with a major movement from Mexico into California happening about a fortnight ago.
I have a question though, will all these large numbers, wouldn't that cause an increase in predators? These are not like monarchs which are poisonous, these can be eaten (as far as I'm aware)