A Clouded Yellow Butterfly Invasion

Abstract

ONE of the most interesting entomological features of the summer of 1941 is the invasion of clouded yellow butterflies (Colias croceus or Edusa) from the Continent which, since the first week of July, have been seen in Lancashire and Cheshire and various other parts of the north of England. This immigration has nothing to do with the War; it is one of the more spasmodic immigrations of insects which occur from time to time, the classic example being the ‘great EdMsa year’ of 1877, when flights ranged from the Orkneys to Land's End and Ireland. Several were seen in 1933, 1926, 1913, 1872, 1864, 1862 and 1859 and odd specimens in the north in other years like 1930. The greenish–white variety helice Hubn. has also been seen, while the rarer pale clouded yellow (C. Hyale) was observed in 1860, 1872, 1891, 1900–1, and at least one specimen has been noted at Ness, west Cheshire, during the present immigration of clouded yellows. A few clouded yellows from south Europe reach the south of England almost every year, arriving during May or June; third brood Larvæ are sometimes found in autumn on trefoil, lucerne or clover, and attempts at hibernation have been noted, but there is no record of surviving the winter here. Excepting in 1892, the common and pale clouded yellows are seldom abundant immigrants together.