Many of the present-day plant and insect pests have arrived in Colorado without the corresponding natural enemy that kept them in check in their native habitat. It is the intent of the Colorado Department of Agriculture to import and release these beneficial insects to suppress populations of introduced pest species. A large root-feeding weevil has proven to be effective for control of spotted knapweed and will be available for use in this program. Eggs are laid near the crown of the plant, just below the soil surface. The larvae mine to the cortex of the root where they feed and spend the winter.
New adults emerge in the spring and begin the egg laying process.
Destruction of the knapweed plants has been accomplished by weevil, thereby showing great potential in suppressing knapweed. A small flea beetle will be available for control of leafy spurge. The adult of this beetle lays its eggs near the base of the plant. The larvae feed on roots and root hairs causing extensive damage to the vigor of the plant. In some areas, large infestations of leafy spurge have been suppressed by the damage caused by these insects.