A small wasp, Trichogramma ostriniae, introduced from China to help control the European corn borer, is a recent example of a long history of classical biological control efforts for this major pest. Many classical biological control programs for insect pests and weeds are under way across the United States and Canada.
A harvestman (a male Phalangium opilio), showing the almost fused arrangement of abdomen and cephalothorax that distinguishes these arachnids from spiders Harvestmen have a pair of prosomatic defensive scent glands ( ozopores ) that secrete a peculiar-smelling fluid when disturbed.
Chemical Control Insecticides have been used to control Pieris rapae since crucifers have been cultivated. Generally, insecticides have to be applied every one or two weeks to achieve good crop quality and this has led to numerous instances of insecticide resistance in P. rapae ( Chou et al., 1984 ; Han et al., 1987 ).