Canada Thistle
Purple Loosestrife
Are there any recent successes in biological control of weeds?

Yes. The biggest success story of the 1980's was the dramatic reduction of tansy ragwort (Senecio jacobaeae) by the Ragwort Flea Beetle (Longitarsus jacobaeae) combined with the defoliating Cinnabar Moth (Tyria jacobaeae). By the early 70's, tansy ragwort had infested tens of thousands of acres of pasture and rangeland along the West Coast. Ragwort Flea Beetles and Cinnabar Moths were then released throughout the Pacific Northwest as part of intensive biological control programs. By the mid-80's, tansy ragwort had been successfully controlled throughout most of its range. In fact, reports from Oregon indicated 90% reductions in ragwort populations!

An equally dramatic success has been the control of leafy spurge by a combination of root-boring flea beetles. Significant declines of spurge in many areas of the Great Plains and Rocky Mountains have been documented in the 1990's.

Recent success has been seen in the control of spotted and diffuse knapweeds, in the current decade as well. The control of these knapweeds has been due to the combined impact of both the root-boring weevil and seed head attacking insects.

Most recently we have seen great success in the control of Dalmatian toadflax with the attack of the Stem-Boring Weevil, Mecinus janthinus,

Biological Control of Weeds, Inc.
1418 Maple Drive • Bozeman, MT 59715
Phone 406-586-5111

Email: bugs@bio-control.com