284 THE ENTOMOLOGIST. 
The great entomological event of the past year has been the 
extraordinary abundance of Pyrameis cardui and Plusia gamma. 
The causes of this, however, are not inherent to this country, as 
both were migrants here, coming originally we know not whence, 
though probably from somewhere in Africa. The swarm, starting 
from N.W. Africa, was observed at Algiers as early as 15th 
to 20th April, travelling in a north-easterly direction ; it reached 
the neighbourhoods of Valencia and Barcelona by April 26th to 
30th, spread over Spain, touching the Balearic Isles May Ist to 
8rd, and erossed the Eastern Pyrenees on May 26th and 27th. 
Tt was distributed over South-east France, Switzerland, and 
North Italy, and on the morning of June 5th thousands of living 
specimens were found on the snow at the Hospice of St. Gothard. 
It then spread over Germany and Austria, being recorded in the 
various localities on dates varying from the 7th to 16th June. 
Another column crossed the Mediterranean to Sicily, and spread 
itself northwards over Italy in June. The more westerly end of 
the migratory swarm reached Strasburg as early as 8rd to 9th 
June, Bisheim (Alsace) on June 8th, Angers and Rennes, in 
France, on June 10th. Paris and its environs were not apparently 
reached till June 15th. It arrived on our south coast on June 
10th, whence it spread throughout the three kingdoms ; specimens 
first noticed here (Maldon) on June 13th. Although I have 
spoken of this extraordinary and unexplained migration in the 
singular, it isnot to be supposed that the multitudes of specimens 
came all in one column; we have direct evidence to the contrary. 
Its tracing does not altogether rest with British entomologists ; 
we know that the swarm was far from exhausted when it reached 
these shores, and P. cardui has occurred almost everywhere in the 
greatest profusion, though possibly not in such immense numbers 
as occurred along the Rhine, where in many localities its resultant 
larvee became a destructive pest to the cultivators of artichokes 
and Artemisia. Many interesting hypotheses have been started 
to account for this true case of butterfly migration, which is not 
altogether a new thing with P. cardui. None appear altogether 
satisfactory. P. cardui is the most widely distributed of all 
lepidopterous insects, and follows the general rule of the animal 
and vegetable kingdoms, that “the most widely spread species 
are those capable of withstanding the greatest climatic changes 
and adapting themselves to the greatest diversities of topography.” 
