158 THE. entomologist's recobd. 



Wolfe notes an immigTation on June 7th, 1899, into south-western 

 Ireland, and for days afterwards they were in great numbers, thou- 

 sands having appeared to arrive simultaneously. LarviB were abundant 

 in July, and pupae 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 larvae in September, so that the continuous-brooded 

 habit was as usual quite evident in the progeny. 



Of the abundance of P. canhd in the countries bordering the shores of 

 the Mediterranean, Eaton writes {Ent. Mo. Mckj., vol. xxx., pp. 98, 133), 

 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, 1891, a spell of cool weather 

 (with snow on the mountains northward) was followed at Biskra with 

 a rise of temperature, and 1\ canliii, which had not hitherto been 

 commoner during the winter than tortoise-shells in England 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 increase 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 over the 

 district or perhaps through emigration. By May 4th the imagines 

 were abundant once more, frequenting the blossoms of many kinds of 

 plants in the desert and crowding to the bushes of Tamarix braclnj- 

 stijlis, now in flower along the Aned Biskra above the barrage. They 

 were not noticed to be ovipositing, and Eaton suggests that perhaps 

 they were awaiting a sirocco to waft them to the highlands of Con- 

 stantine and Setif, if not to Europe. 



This cosmopolitan 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 [Fhit. Ncivs, vi., p. 150) an account of a swarm ol Pi/ra- 

 vieis cardui 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- 



