iOvlO1900 ik^r 



JOURNAL OF VARIATION. 



Vol. XII. No. 10. October 15th, 1900. 



Migration and Dispersal of Insects : Lepidoptera. 



By J. W. TUTT, F.E.S. 

 Besides the two species of Coliads (0. edma and C. hyale) and 

 Pyraineis cardid, to which reference has ak'eady been made, Piei'is 

 daplidicc, Argynnis lathonia and Kuvanessa antiopa, also, can only be 

 considered to be British species, so far as the immigrants themselves, and 

 the direct progeny of these immigrants are, for the rest of the summer 

 months directly folloAving their arrival, able to exist here. The 

 appearance of these species in this country is very uncertain, and their 

 numbers always much fewer than those of the three first-named species, 

 although in some years they are moderately abundant. It were 

 perhaps useless to trace the years in which these species have occurred 

 commonly in Britain. Generally, in such years, a few examples in the 

 early summer are followed by an unusual abundance in autumn ; 



t suggesting that the former are the immigrants and the latter British- 

 bred, ki any rate these species exemplify well that particular group 

 of insects that repeatedly become extinct in the higher temperate 

 regions, and would never be seen in these districts Avere it not for the 

 bccasional influx of immigrants. Stephens, in 1835, noted {lllus, 

 0aust., i., p. -45) that "till about the middle of the last century few 

 specimens of E. antiopa had been observed, but about 60 years since, 

 it appeared in such prodigious numbers throughout the kingdom that 

 "' the entomologists of that day gave it the name of the Grand Surprise. 

 Of late it has again become infrequent ; the last time that it occurred 

 in plenty, according to Donovan, being in 1789 and 1803, a few only 

 having been captured subsequently. At the present day (1835) it still 

 appears to occur occasionally throughout England, as Mr. Backhouse 

 informs me that it has been found repeatedly near Seaton, Durham, 

 and often floating on the river Tees." Wailes, on the authority of 

 Backhouse, states that " about 1820 he saw vast numbers of this 

 species strewing the seashore at Seaton-Carew, both in a dead and living 

 state." We may here point out that Hewitson notes {Eat. 2Io. 

 Mai/., ix., p. 161) that, on one occasion whilst crossing from Boulogne, 

 he saw an example of this species midway in the Channel. In the 

 year 1819 it was specially common in Durham and Suffolk, and in 

 1816 in all the eastern and southern counties from Hampshire to York- 

 shire and also in Ayrshire ; it was not uncommon in 1859-1860, but 

 the greatest year for this species was 1872, when some hundreds were 

 taken, its range extending, on this occasion, from Southsea and Dover to 



