ABSTRACT
The processes of natural biological control maintain the so-called balance of nature. Biological control is defined as the planned use of living organisms to reduce the vigor, reproductive capacity, density, or effects of undesirable plants. Of practical necessity, it should aim for low host population numbers rather than eradication. Biological control with introduced species of insects and other control agents carries considerable potential that the predator may increase in numbers, change host plants, and attack species of economic importance. It is more extensive and has been highly successful with agricultural pests because of great economic need to produce food and fiber crops. Biological control of annual species, such as Halogeton glomeratus, may be most effective with seed-destroying insects, but annual weeds in particular must also be attacked ecologically through competition from perennial grasses. It has a bright future as a component of ecological rangeland management.
