This is a large creamy-white butterfly peculiar to the Canary Islands.
It is found in some numbers on and near the coast of Teneriffe
from April to September; the time of its appearance, however,
varies somewhat in different years. The larva is smooth, and has a
ground-colour of grey, finely dotted over with black spots. There
is a yellow stripe on the back and along each side. It feeds on the
nasturtium gregariously, and the pupa attaches itself, head downwards,
to a wall near the plant.
The female butterfly, the underside of which is illustrated, has a long
uneven blotch of black on the surface of the fore-wings; the male has
none. The upper surface of both sexes is cream-white, with a black
apical patch on the fore-wings. The under-sides have the long black
blotch as seen on the surface of the female, and the ground-colour
of both is yellow, finely sprinkled with black dots. The measurement
across the wings varies from two and a half to three and a half inches.
It is best to procure the larvæ to obtain good specimens, but
the Ichneumon fly is such an enemy to this species that great
disappointment will probably be experienced in the rearing if the
caterpillars are not well examined before being placed in the
breeding-cages.