BRIMSTONE CLOUDED YELLOW. 53 



Plentiful as this butterfly is in all the southern 

 counties, and extending in more or less abundance as 

 far northwards as the lake district, it there becomes 

 scarce ; and I can find no instance of its having 

 occurred in Scotland. 



Of course, its prevalence in any district is naturally 

 regulated by the abundance of its food-plants, the 

 buckthorns. 



Gardens, fields, and lanes are equally the resort of 

 this favourite insect ; and there the newly-hatched spe- 

 cimens are to be found on the wing from August to 

 October. 



THE CLOUDED YELLOW, OE CLOUDED 

 SAFFKOK (Colias Edusa.) 



(Plate III. fig. 3, Male ; SA, Female.) 



THIS richly-coloured and nimble-winged fly is ever the 

 darling of the collector. None make a finer show in 

 the cabinet, and few tempt pursuit more strongly than 

 does this golden beauty when on the wing. 



For many years past, and up to quite a recent period, 

 the appearance of this butterfly in any abundance was 

 a phenomenon only occurring at uncertain periods, 

 separated by intervals of several years. In one season, 

 perhaps, hardly a solitary specimen would be seen, and 

 in the very next, a swarm of them would spread over 

 the southern counties, delighting the fly-catcher, and 

 puzzling the naturalist to find a sufficient reason for 

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

 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, nolens, 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 



