GONOPTERYX RHAMNI. 71 



again, and it is always one of the earliest butterflies 

 to appear in the spring. As is th case with others 

 that hibernate, the sexes take no notice of each other 

 in the autumn, but pairing takes place and the eggs 

 are laid after the winter's sleep is over. It does not 

 hide its charms in solitary places, but courts the road- 

 side and the garden. It is not easily scared, and, if 

 the net does not enclose it at the first sweep, there is 

 usually a chance for a second ; nor is it a particu- 

 larly active flyer, though its powerful wings appear to be 

 specially adapted for rapid flight. 



For a wonder the names of the Brimstone Butterfly 

 are well bestowed. The common name accurately de- 

 scribes the colour of the male insect, the angles of the 

 wings are referred to in the generic name, Gonopteryx 

 (angle-wing), while the specific name rhamni calls atten- 

 tion to the plants on which the larvae feed : these are 

 the two species of Buckthorn (Rhamnus catharticus and 

 R. Franguld], on the twigs of which the eggs are laid 

 singly towards the end of April. 



The larva (Fig. 61) hatches out of the conical yellow 

 egg in about a fortnight, 'and is full-fed towards the end 

 of June. The general colour is bright green, and the 

 surface is covered with small black points. 



The chrysalis (Fig. 62), which is bright green with 

 brownish markings, is to be found on the twigs or under 

 the leaves of the food-plant, hanging by the tail from a 

 pad of silk, which the caterpillar placed beforehand on 

 the twig or leaf. It is further kept in position by a loop 

 of silk stretched across its back and fastened at both ends 

 to whatever support the caterpillar had selected. After 

 twenty days the perfect insect emerges from the chrysalis. 



The ground-colour of the upper surface (Fig. 59) of 

 the male Brimstone Butterfly is a bright yellow, like 



