I have, this year, grown some crimson-flowered nasturtiums in a
pot and, needless to say, the white butterflies soon found them.
Before long both large white (Pieris brassicae) and small white
(Pieris rapae) caterpillars appeared, the large whites (below)
being particularly obvious on the leaves and flowers. This
morning nearly all these caterpillars had disappeared and a
couple of wasps were spotted searching the plants for more. By
the evening all I could find was a solitary small white (below)
that had survived, perhaps, because of its more cryptic
colouring. Caterpillars of the white butterfly family, the
Pieridae, store toxic chemicals derived from their foodplants
within their bodies making them distasteful to some of their
predators, mainly birds. That is why the large white larvae feel
safe to feed openly on the foodplants and have a black and
yellow pattern of colour that acts as an " I taste nasty"
warning. While it may offer some protection against birds it
does not stop the wasps and various other