Insecticides are used to control insect pests, such as
weevils, bertha army worm, cutworm, diamond-back moth larvae, and grasshoppers.
These insects have natural regulators, such as weather, parasites, predators and
disease. But when these regulators fail to control populations, the economic
impact of insect pests can be significant. Chemical insecticides can give the
needed additional population control.
Insect infestations do not occur every year and they are
often limited in the areas affected. As a result, Alberta farmers use much less
insecticide than herbicide. A 1996 census indicated that only 3.7 percent of
farms applied insecticide to 300,000 hectares.
Two important insect pests that are responsible for
widespread damage and economic loss are the bertha army worm and the
grasshopper. Infestations of bertha army worms may be localized or spread over
hundreds of thousands of hectares of canola, and their populations fluctuate
widely from year to year. Grasshoppers are mainly grass eaters, so their damage
is confined primarily to cereal crops, especially wheat and barley. Grasshopper
infestations usually peak in drought years.
Department of the Environment. State of the Environment Report, Terrestrial Ecosystems. Edmonton: n.p., 2001. With permission from Alberta Environment.