The British Butterflies Described 



it is plentiful, while in others hardly a specimen will be 

 seen and as for the caterpillars, we never hear of them 

 being successfully searched for. The probability is that 

 from a few spring visitors from the Continent we get a 

 number of descendants in August, when a great many 

 more arrive from across the Channel and mingle with 

 them. The distribution of nearly all animals is 

 regulated by the food-supply, the climate, or their 

 enemies ; yet none of these seem to satisfactorily 

 account for the disappearance and reappearance of 

 Edusa with us. It is a strong flying insect with a 

 roving disposition, and on quite a few occasions it has 

 been noted as far north as Arran and the Ayrshire coast, 

 in Scotland. The brilliant orange and black wings 

 make its identity unmistakable. Not so, however, 

 with the light sulphur-coloured female variety, which 

 very nearly approaches the typical female form of 

 Hyale y but it may be distinguished by the broader black 

 band on both fore- and hind- wings, and a heavy sprinkling 

 of black scales near the base of the former, and all over 

 the latter. The orange spot, too, in the centre of the 

 hind-wing is deeper, and, being on a darker ground, 

 looks much brighter. There is no corresponding male 

 variation. 



The caterpillar is dark green, with a light line on 

 each side, varied with yellow and orange touches. It 

 feeds on various plants of the pea order vetches, 

 trefoils, clovers, etc. The chrysalis is brown spotted, 

 and is striped with a yellow line. The butterfly 

 appears with us during August and September. 

 40 



