72 BRITISH BUTTERFLIES. 



this sudden burst of insect-life. Whether the eggs laj 

 dormant for years, till hatched under peculiarly favour* 

 able conditions ; or whether every now and then a few 

 individuals were tempted to cross the Channel from the 

 Continent by some attraction unknown to us, or were, 

 nolens, volens, blown hither by the wind, and then 

 deposited eggs which produced the next year's troop of 

 butterflies ; or, lastly, whether an agency was at work 

 here, of whose nature we are entirely ignorant, all 

 these are questions that still remain to be answered. 

 There is, I believe, no foundation for the opinion some- 

 times held by entomologists, that this species prevails at 

 regular periods, such as once in four, or once in seven 

 years. In fact, for the last two or three years its per- 

 manent residence and appearance among us seems to be 

 established, while, at the same time, its northward 

 range has been greatly extended, a considerable number 

 having been taken even in Scotland its existence in 

 that country having keen previously quite unheard of. 



The environs of London, especially on the south side, 

 have been abundantly visited by this charming insect ; 

 but its tastes have a decidedly maritime tendency, and 

 wo find it has a marked preference for the South Coast; 

 abounding, again, more especially towards the eastern 

 end. Its favourite resorts are clover and lucerne fields, 

 though dry flowery meadows, open downs, and the sides 

 of railway-banks are also the scenes of its lively flight 

 *Dr Edusa has indeed a lively flight, and his pursuer 

 has need oi' the "?even-league boots," with the hand of 



