158 | THE ENTOMOLOGIST’S RECORD. 
Wolfe notes an immigration on June 7th, 1899, into south-western 
Treland, and for days afterwards they were in great numbers, thou- 
sands having appeared to arrive simultaneously. Larvee were abundant 
in July, and pup also, yet there was no great number noticeable in 
August, and Wolfe suggests that some strange instinct caused most of 
those that emerged to leave. The eggs that were laid in August pro- 
vided full-fed larvee in September, so that the continuous-brooded 
habit was as usual quite evident in the progeny. 
Of the abundance of P. cardi in the countries bordering the shores of 
the Mediterranean, Eaton writes (Ht. Mo. May., vol. xxx., pp. 98, 183), 
that at the base of the Azures and south of the Hodna in eastern Algeria, 
the Ziban, with Biskra as the chief town, forms the northern border 
of the Sahara. At the end of March, 1894, a spell of cool weather 
(with snow on the mountains northward) was followed at Biskra with 
a rise of temperature, and P. cardui, which had not hitherto been 
commoner during the winter than tortoise-shells in Iineland are apt to 
be in early spring, increased rapidly in numbers daily, until the butter- 
flies became as plentiful as Garden Whites in June over a cabbage plot 
or Meadow Browns in a well-stocked hay-field. A certain proportion 
of this inerease in population was undoubtedly due to some bred in the 
vicinage, because specimens were seen brightly coloured and in fine 
condition amongst the faded and worn, and a cripple was observed one 
day with its wings not fully expanded. But the greater number must 
have wandered hither with the wind from southern districts to loiter 
in the welcome shelter of hillsides and hollows. They laid their eggs 
in various places. By April 11th the species (though still very common) 
was in diminished numbers, perhaps through dispersion oyer the 
district or perhaps through emigration. By May 4th the imagines 
were abundant once more, “frequentine the blossoms of many kinds of 
plants in the desert and crowding to the bushes of Tamarix brachy- 
stylis, now in flower along the Aned Biskra above the barrage. They 
were not noticed to be ovipositing, and Haton suggests that perhaps 
they were awaiting a sirocco to waft them to the highlands of Con- 
stantine and Sétif, if not to Europe. 
This cosmopohtan butterfly is not only a migrant in Europe, but 
Bowles relates (Canadian Ent.) that the species also migrates in North 
America, and instances the year 1865 or 1866 as one in which a 
migration took place in the neighbourhood of Quebec. For many 
years it had been quite absent in that district, until, one summer, it 
suddenly became the commonest butterfly in the neighbourhood. ‘The 
next year it was again absent, and it did not reappear for many years. 
Franham gives (nt. News, vi., p. 150) an account of a swarm of Pyra- 
mets cardut observed in California and Nassig, and passing from north to 
south, in April, 1895. He estimated that from 9 a.m. until noon 
some 200 butterflies passed per minute, in a lane about 80 rods long; 
at 2 p.m. about 50 passed in that time; but at 4 p.m. only an occasional 
specimen was seen. 
It is interesting to recall the fact that the common thistle on which 
the caterpillars of this butterfly chiefly feed is also a notable migrant, 
and to note that during recent years the thistle has widely spread, and 
that great thickets of this plant are now to be found in various parts 
of North America, where it has often ousted the native weeds. It 
would appear that, as the boundaries of the insect’s roaming capa- 
