156 THE ENTOMOLOGIST S RECORD. 
In 1880 there was scarcely a record of the insect occurring in these 
countries, so completely had the species, by attempting to keep up its 
southern habit of continuous-broodedness, exterminated itself. P 
As we have already stated, many entomologists recorded their 
observations, and soa considerable amount of evidence was forthcoming. 
Ritter says that he was by the edge of a forest near Nikolsburg in 
Moravia, on a hot sunny day at the end of May, when, at about two 
o'clock in the afternoon, he noticed a peculiar humming sound, and 
immediately afterwards observed an enormous flight of butterflies, 
which came in a westerly direction over an open forest park, and pitched, 
as if by common consent, on the sunny wall opposite to him. Hurrying 
off to bring others to witness the sight, he returned in five minutes, 
but found only one or two individuals instead of the many thousands 
he had left there. The swarm appeared at Treviso, north of Venice, 
between May 30th and June 6th. Ninni remarks that on the 30th 
there were comparatively few butterflies all of which were passing in a 
north-westerly direction ; on the 31st the same condition of affairs 
existed, the wind at this time coming chiefly from the north ; on June 
1st, with the wind west of north, they moved in a direction to the east 
of north, and this direction they retained for the three following days ; 
on the 2nd they came in immense numbers, flying from 5.15 a.m. 
until sunset, the wind varying on either side of north; on the 8rd the 
numbers though still great had begun to decrease; the prevailing wind 
was from the north-east, and they were flying directly against the 
wind, which had now attained greater strength; on the 4th, with the 
wind from a more southerly quarter, they moved in the same direction 
as before, but were only noticed at certain points ; on the 5th, with 
the wind in an easterly direction, the numbers were about the same as 
on the previous day, while on the 6th with the prevailing wind from 
the north-east, the flight only began at one o’clock in the afternoon, 
and did not last for more than an hour and a half. 
In the early days of June, and particularly about the 7th, the 
butterflies appeared all over the central portions of Europe, moving, 
asa general rule, at right angles to or against the wind, but with a 
_ prevailing direction from the south-west to the north-east. They 
passed over all obstacles without hesitation; thus on June 5th, as we 
have already noticed, thousands of them were found dead on the snow 
around the St. Gothard hospice, only a day or two after which they 
appeared in immense swarms to the north of the Alps. That it was 
not simply a superabundance of butterflies already existing in the 
region, but an influx from outside, seems to be abundantly proved by 
the facts, viz., that P. cardwi does not normally appear upon the wing 
(except perhaps a few hybernated specimens) until the middle or end 
of July, whilst this invasion took place at the end of May and during 
the first half of June; and secondly by the condition of the speci- 
mens themselves. Wherever captured all the specimens noted were 
worn and faded, indicating that they had flown for an immense distance. 
M. Oberthiir, on capturing specimens of the swarm which made its 
appearance at Rennes on June 10th, remarked that they belonged to a 
very characteristic African type, noticeable from the fact that the 
brighter parts of the upper wings are very much paler and less rosy 
than in the form found in France. Indeed, he considered many to be 
precisely like specimens from Abyssinia which he had in his collection. 
