Biological Insect Releases

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
  • Tansy ragwort
  • Purple loosestrife •Canada thistle
  • Scotch broom
  • 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
  • Dalmatian toadflax
  • Meadow knapweed •Diffuse knapweed
  • Spotted 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:
    2010Bruchidus villosus - 1,300
    Exapion fuscirostre- 100

    2011B. villosus - 600

    2012B. villosus - 10,000

    Mecinus janthiniforms - 200
    2013B. villosus- 300
    E. fuscirostre - 300
    Larinus obtusus - 500L. obtusus - 500L. obtusus - 250M. janthiniformis - 400
    2014B. villosus- 600L. obtusus - 500
    L. minutus - 250
    Bangasternus fausti - 250
    M. janthiniformis- 400
    2015B. villosus- 1,600L. obtusus- 1,500
    L. minutus- 550
    B. fausti- 350
    M. janthiniformis- 200
    2016B. villosus- 2,000L. obtusus- 700L. obtusus- 500L. minutus-315
    B. fausti- 435
    M. janthiniformis- 600
     2017B. villosus- 900
    E. fascirostre- 100
    L. obtusus- 250
    B. fausti- 434
    L. obtusus- 500
    L. minutus- 266

    2018B. villosus- 1,600L. obtusus- 400B. fausti- 750


Bruchidus villosus.jpg
Bruchidus villosus
Exapion fuscirostre.jpg
Exapion fuscirostre

Dalmation toad flax bio release 61008 004.jpg
Mecinus janthiniformis

Diffuse knapweed beetleLarinus minutus 
Meadow knapweed insects
Larinus obtusus
Bangasternus fausti.jpg
 Bangasternus fausti