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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:

 2010 Bruchidus villosus - 1,300
Exapion fuscirostre- 100
 2011 B. villosus - 600        
 2012 B. villosus - 10,000        Mecinus janthiniforms - 200
 2013 B. villosus- 300
E. fuscirostre - 300
 Larinus obtusus - 500  L. obtusus - 500 L. obtusus - 250  M. janthiniformis - 400
 2014 B. villosus- 600 L. obtusus - 500    L. minutus - 250
Bangasternus fausti - 250
M. janthiniformis- 400
 2015 B. villosus- 1,600 L. obtusus- 1,500   L. minutus- 550
B. fausti- 350
M. janthiniformis- 200
 2016  B. villosus- 2,000  L. obtusus- 700 L. obtusus- 500 L. minutus-315
B. fausti- 435
 M. janthiniformis- 600
 2017  B. villosus- 900
E. fascirostre- 100
L. obtusus- 250
B. fausti- 434
L. obtusus- 500
L. minutus- 266
 2018  B. villosus- 1,600  L. obtusus- 400 B. fausti- 750    

Bruchidus villosus.jpg
Bruchidus villosus

Exapion fuscirostre.jpg
Exapion fuscirostre

Dalmation toad flax bio release 61008 004.jpg
  Mecinus janthiniformis

Diffuse knapweed beetle Larinus minutus 

Meadow knapweed insects
Larinus obtusus

Bangasternus fausti.jpg
Bangasternus fausti

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