Original: The larvae ( caterpillars ) of a few of these species , such as Pieris brassicae and Pieris rapae , commonly seen in gardens , feed on brassicas , and are notorious agricultural pests .
Simplified: The caterpillars of a few of these species , such as Pieris brassicae and Pieris rapae , feed on brassicas . They are commonly seen in gardens and are agricultural pests .