Vanessa at night - no 2

Nick Greatorex-Davies ngd at
Wed Jan 23 15:25:06 EST 2002

Hi all,

The promised second installment:

Another response to my request to uk-leps for any evidence for night flying butterflies produced the following from Ian Waller (repeated with permission):

Nick G-D


The following, is taken from

Natural History Transactions of Northumberland, Durham, and Newcastle-
Upon-Tyne. [UK]
Vol XII Part I

John Robson 1899

Pieris Brassicae (Linn.). LARGE WHITE

Large swarms of the species have occasionally been observed and it was
once the writer's privilege at Hartlepool to witness the passage of one
of these migratory hordes. An account of it has already appeared in
print,(*) but it has not often fallen to the lot of an Entomologist to
see such an occurrence, it may be worth while briefly to refer to the
matter here. It was a very hot day in July, 1867, and at 9 a.m., when I
went to business, I noticed an unusual number of white Butterflies in
the street. Lads on there way to school were chasing them, and one or
two were already in view. As the day wore on the numbers steadily
increased, and by 11 a.m. a dozen or twenty might have been seen flying
down the street, their places being taken by others as they passed on.
Those, however, were but the advanced guard, the great army was yet to
come. By noon they were flying in hundreds, and by two in the afternoon
there were thousands of them to be seen at once, all flying in one
direction from east to west. The appearance of such an enormous number
of Butterflies all flying at the same time was most extraordinary, and
attracted the attention of the most unobservant. When Darwin witnessed a
similar flight of the coast of South America, the sailors said it was
"snowing butterflies," and no phrase seemed so appropriate for what I
saw. their white colour, and somewhat irregular flight, made them
exactly resemble a heavy fall of large flakes of snow. They continued to
pass in undiminished numbers till towards five o'clock, when a sudden
thunderstorm and very heavy rain came on. Such of the Butterflies that
did not obtain shelter in doorways, window reveils, or under shop
cornices, were quickly driven to the ground, where they were pelted to
death by the rain, or floated in hundreds along the flooded channels.
When the rain ceased, the day was too far advanced for flight to be
resumed. Next day there was a very large number about the streets, but
they flew in a desultory manner, and entirely without the steady,
purpose-like flight of the day before. I made every possible enquiry as
the origin of this enormous swarm of white Butterflies, but beyond the
fact they appeared to come from the open sea I could not learn anything
about them. Fishermen who had been in they bay had noticed them. The sea
was perfectly smooth and there was no wind to ruffle the surface. one or
two of the more observant had noticed that the Butterflies lit on the
surface of the water, rested there for a little while, and then rose
again and pursued their flight. From what I could make out of the extent
of the column, I estimated that the denser portion was about 100 yards
wide, but the stragglers on either side extended very much further. the
length of it much have been very great, for though they did not seem to
advance beyond from about two to three miles per hour, yet even the
denser portion of the swarm was quite four hours in passing, and had not
commenced to decrease in numbers when the storm dispersed them. I seems
impossible to form any estimate of their immense numbers, but, however
incredible it may appear, there must have been millions of them. Where
they all came from is a very puzzling question, and unless they
travelled across the sea at a much quicker rate, they would require
several days to cross from the nearest part of the continent. It seems
difficult to believe they could accomplish this, yet there can be no
doubt that an American Butterfly, Anosia plexippus, has more than once
crossed the Atlantic and reached our shores in considerable numbers.
(*) Young Naturalist, Vol II., p.29.

I would like to add to this by relating an account as it was told to
myself (I.J.Waller). Apologises as I can not remember who told me.

"I had left some moth traps on the coast (south?) and just before dawn,
I set out to see what had turned up. As I approached the coast I could
see a cloud moving towards land, as it neared I realised it was actually
a cloud of Large Whites making landfall. As the sun had not rose, those
butterflies must have travelled over the water through the night".


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