Biological Controls (insects) are helping to control infestations of several invasive and noxious weed species found in Cowlitz County. Biological insects are approved for release by the Federal government and are moved around in our state through the Washington State Department of Agriculture and the King County WSU Extension office in a coordinated effort with each county Noxious Weed Program in the state of Washington.
Releases prior to 2010
Purple loosestrife •Canada thistle
Dalmatian toadflax and the •Knapweed complex weeds Biological insects prior to 2010 were released by the Weed Board, Cowlitz County and the WSU Extension Biocontrol program. 2010 to 2018 Releases
Meadow knapweed •Diffuse knapweed
Scotch broom A total of seven host-specific biological control insects have been released to control the noxious weeds listed above. Other biological insect species that were released throughout Washington State have also found their way into our county to help fight noxious weed infestations. Here are the total number of biocontrol insects release by year per plant species: