Brief SummaryRead full entry BiologyTypically, two generations
are produced each year (3). The first brood of adults emerges in
spring and flies until April. A second, larger brood of adults
appears in July (2), and in particularly warm years, a third
brood may occasionally occur (2). The eggs are laid in batches,
on leaves of the foodplants (2), hatching after around a week
(3). In their early stages, the caterpillars live in groups (2),
and can be extremely damaging, reducing the foodplant to a mere
skeleton (3). They become solitary later on in life (2), and are
very distasteful to birds because they consume mustard oils from
their diet (2); their bright colouring advertises this fact,
protecting the caterpillars from attack (3). Members of the
broods produced later in the year hibernate through the winter
as a white pupa (2) attached to walls, fences, tree trunks and
occasionally the foodplant (3).