The British Isles is currently having the most spectacular immigration
of butterflies for decades, if not centuries. Painted Ladies are
arriving in their tens if not hundreds of millions.

Picture taken in my garden:

http://s214580749.websitehome.co.uk/...aintedLady.jpg

Anyway, the weather aspect started over the winter when the Atlas
Mountains in North Africa had ideal growing conditions for the plants
that the butterfly caterpillars feed on – plenty of rain and adequate
sunshine. The butterflies moved to Spain and France and then bred.
We are now getting the offspring, ie the next-but-one generation from
the North African one.

Now an exactly parallel situation has occurred in North America where
huge number of Painted Lady butterflies has reached California from
wintering sites in Mexico. Presumably (parts of) Mexico also enjoyed
good winter rains.

I have to wonder if there is any correlation with El Nino or La Nina
events. Of course for we butterfly enthusiasts in Britain, this is
merely an exciting event. But, and this is the big question, could
population explosions of less benign insect such as locusts be
correlated with El Nino events? If it were possible to predict such
explosions based on weather data, then suitable eradication methods
might be possible in the source breeding grounds.
So can anyone point to recent weather data for the Atlas Mountains and
Mexico as compared to long term averages?

Jack