Classical biocontrol involves the importation of exotic natural enemies in an attempt to control exotic pests.

EXAMPLES

Larch casebearer. The larch casebearer, Coleophora laricella, was introduced into New England from Europe around the middle of the last century (slide). In 1957 it was discovered on western larch near Coeur d'Alene, Idaho. It spread rapidly throughout the larch forests of the interior Northwest, and caused widespread defoliation for many years (Slide). Several parasitic Hymenoptera were introduced from Europe in an attempt to control larch casebearer populations. One of these parasitoids, a braconid Agathis pumila (Ichneumonoidea), has brought the casebearer under effective control so that defoliation by this insect is no longer a problem (slide).

Klamath weed. When St. John's wort or Klamath weed, Hypericum perforatum (slide), was introduced into western North America from Australia it took over large areas of rangeland (slide). Several herbivorous insects were introduced from Australia in an attempt to control the weed but it was the chrysomelid beetle, Chrysolina quadrigemina (slide), which brought the weed under complete control (slide). Humbolt County ranchers were so impressed by the control of the weed that they built a monument to the Klamath weed beetle (slide). Another famous example is the biological control of the prickly pear cactus by a moth (slide).

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