54 THE BUTTERFLIES OF THE BRITISH ISLES. 



in almost every county in England and Wales, Ireland and 

 Scotland, extending even to the Orkney Islands (1877). 



Its home appears to be in North Africa and South Europe, 

 whence it spreads over the greater part of Europe and Western 

 Asia. 



Note. — According to Kirby, this butterfly should be called 

 Eurymus hyale, Linn., and the Pale Clouded Yellow be known 

 as Eurymus kirby 7, Lewis. 



The Brimstone (Gonepteryx rhamni). 



This butterfly (Plate 26) has the tips of the fore wings sharply 

 pointed, and there is a rather acute angle about the middle of 

 the outer margin of the hind wings. The colour of the male is 

 bright sulphur yellow, with a central orange spot on each wing, 

 that on the hind wings usually the largest ; there is also a rusty 

 dot at the outer end of the upper veins and along the front 

 margin of the fore wings towards the tip. The female is green- 

 ish yellow, and is marked similarly to the male. In both sexes 

 the horns {antenncE) are reddish, and the long silky hair on the 

 thorax is a noticeable character. It is probably this insect to 

 which the name "butter-coloured fly," contracted into butterfly, 

 was first given ; anyway, it is the only species to which the 

 name applies so well. 



The egg. If the under sides of the leaves of buckthorn 

 {Rhamnus catharticus) or of the berry-bearing alder (R.fran- 

 guld) are examined in May or June, the eggs of this butterfly 

 may be found thereon. They are often placed on a rib of the 

 leaf, but sometimes they are laid as shown in the illustration 

 (Plate 25). At first the colour is pale greenish and rather 

 glossy, but it soon changes to yellowish, and later on, when the 

 caterpillar has formed inside, to a dull purplish-grey. 



The caterpillar when full grown is green, merging into 

 bluish-green on the sides, thickly powdered with shining black 



