Reference

The root weevil Cyphocleonus achates was introduced into western Montana in 1988 as a biological control agent against spotted knapweed (Centaurea maculosa), an exotic invasive weed from Eurasia.Spotted knapweed has declining in areas where C. achates was released, and experiments were conducted to evaluate the role this weevil may play in knapweed decline.

Cyphocleonus achates has been reported to reduce spotted knapweed densities by 77 to 99%, while C. achates in combination with Larinus species can reduce seed production by 94% in some cases. Dalmatian toadflax: The stem-mining weevil Mecinus janthinus (Fig. 3) is a biocontrol agent of Dalmatian toadflax that is effective in some warmer areas of

Large-scale control against diffuse knapweed has been seen at a number of locations along the Front Range. The Insectary currently releases this agent as the primary biocontrol for diffuse knapweed. The root-boring weevil Cyphocleonus achates weakens plants by destroying the root system. This large weevil has been effective against both diffuse